I recently purchased an s2k and noticed that it idle'd a bit rough.

Took it into a local (trusted) shop to take a look at it. They suggested cleaning the injectors and having valves adjustment.
Did that, idle is still rough (it holds RPM's, but you can feel it in the cabin a lot).

So we did a compression test and it turns out that #4 is low (around 134). The others are at 175-180.
He determined that the leak is either from scoring in the cylinder (he put oil in it), or a bad gasket (both very common for #4).

My question is, could it be something else? Should i look for anything else?
I plan to take it to another mechanic, purely to get a second opinion.

The car has no CELs (in the 700miles ive had it), and no smoke. 2007 71k ODO.

 

If he put oil in, did the compression come up?

There really aren't more reasons then;
1. Rings
2. Valves
3. HG