To give an update..I was able to do a compression check. Everything looks normal there. This was done on a cold motor, but my readings look normal still. Did 3 tests on each cylinder, my average reading was...

cylinder 1 - 245
cylinder 2 - 243
cylinder 3 - 236
cylinder 4 - 236

since I had the spark plugs out I inspected them and noticed the spark plug in cylinder 4 was wet. I smelled it and it smelled like gas. All other spark plugs were dry, but were pretty black, which leads me to believe the car is running rich regardless. Something is definitely going on in cylinder 4 though. I'm thinking either spark plug is bad, fuel injector stuck/bad, coil bad, or combination of them on cylinder 4. Anyone have thoughts on this? Is it normal for our plugs to be pretty black with carbon on the others? I really can't remember what my spark plugs looked like when I changed them back at 100k miles I just remember them looking like it was time for some new ones.

 

Sounds like you have a great clue with the spark plug condition. Black is not the way mine look. Probably running rich. Now to figure out why?

ECU reset? Its free and you never know!
My thought process is that it is either getting too much gas, or not enough air. Thoughts turn to checking for clean air filter, but I suspect it is fine. Next thought I have is fuel injectors. But, lots of folks here with way more knowledge than I have. Are the plugs really old, or are they fresh?

 

Phew - those are healthy numbers for your compression test.

If cylinder 4's spark plug was wet then this could mean:

1.) Head gasket needs to be replaced
2.) Potentional valvetrain issue - you mentioned that the valvetrain adjustment was performed at 40k? Perhaps it's time to schedule a valvetrain adjustment again since you're over 100k miles now
3.) Timing chain tdc misalignment
4.) What is the condition of your air filter? Are you still using the stock OEM airbox - if so, remove the entire box to inspect if there is anything inside/ clean it . Yes, I know this is silly but the issue could also be a clogged filter.

When you last replaced your spark plugs, did you remember to gap them?

 

I have seen a few threads already where people have a stuck injector spraying to much fuel and then washing out the cylinder and leading to a bad motor, i would address this issue before you drive it much more.

 

Got some great responses! I replaced all my spark plugs today with the oem ngk platinums. My car now fires up fine with no hesitation, but still runs really rough in low rpms and smells like straight gas/really really rich. I'm assuming cylinder 4 is still getting flooded with gas still. It does seem to smoothen out when you rev the car up and get the rpms high.

- valve adjustment was done around 100k (currently has 145k)
- air filter was just cleaned (k&n reusable drop in filter)
- last time plugs were replaced was around 90k and they were properly gapped
- disconnected battery for an ecu reset when I changed plugs, but no luck there
- i have not done the map whack, but am a bit hesitant as I dont want to risk breaking it and making things worse. I'll give it a shot though. Might fix my running too rich on all cylinders issue.

Here are my current thoughts. I'm leaning towards a stuck injector spraying too much in cylinder 4 during low rpms. Logically it would be spraying more fuel in higher rpms, so I'm assuming that's why it smoothens up when I rev it up. If it was the coil I'd assume it would sputter worse as rpms build up due to lack of proper spark and more fuel. Anyone else think it would be the injector as the main culprit? I'd like to get the car running normal again, and then start to address my too rich issue by cleaning the IAC, map wack, ecu reset, monitor my plugs to see how there are looking over time. Any extra thoughts would help

 

ok so I sucked it up and did the map whack. Still sputtering in low rpms, and smells super rich. I'm guessing cylinder 4 is still getting flooded out. Stuck injector next culprit?

 

Yup.

 

finally got a new injector today and put it in. The car fired right up, but still idled very rough. The rpms would drop and then go up. Almost like the care was pulsing while sputtering a bit. Good thing is that this time around it didn't smell like straight fuel, and smelled normal, so I'm thinking that the injector needed to be replaced, but there is still something going on.

When I reved the car up it would smoothen out, so I took it for a quick drive around my block to see if it would go away. It drove fine as long as I kept the rpms up. The second I hit the clutch and it dropped to idle, the car would sputter and even stalled out on me. I started it back up and got it closer to my house, but it stalled again. Started it one more time and got it in the garage. When I turned the car off; I tried to start it and nothing. It's back to what is was doing before I changed spark plugs. I'm wondering if the bad injector killed my new spark plug that i put in cylinder 4. This time around my car finally gave me a CEL, so I'm going to get ahold of an OBD scanner to see what's causing the code. Hopefully it doesnt just tell me its misfiring, and gives me something to work with, so I can figure out what is going on. Maybe fuel pressure regulator? Not sure what to think at this point :\

 

Hooked up an obd scanner to check codes and I'm getting

P0303 - misfire cylinder 3
P0301 - misfire cylinder 1
P0304 - misfire cylinder 4
P0300 - random misfire
P1399 - not sure on this, but assuming it's a misfire code

cat, 02s, and eva were also flashing on the obd scanner

This is what has been done....
-changed all spark plugs and checked gaps (OEM NGK's)
-compression test came back good
-air filter cleaned
-did a map whack
-ecu reset
-replaced injector on cylinder 4 (originally though this was cause)
-valve adjustment was just done 45k miles ago, so that should be ok there.

still at a loss here, but I'm thinking to try fuel pressure regulator next. Any more input would be greatly appreciated. I don't want to keep spending money on random parts that don't need to be replaced..

 

Following up on your spark plug change, did you also change your ignition coil pack?

The misfires are generally tied to bad coils.