its very odd that your not getting a cel

 

this sounds like a problem I had when my synapse engineering missing link stopped working... The one way valve inside started letting air go both ways so I got a major vacuum leak right under the map sensor causing my car to run very very very rich... Check ur map sensor and check for vacuum leaks.

 

replaced o2 and isuue still occuring

 

Do a compression and leak down test. This will give you a idea what's up with the internals. Also tell you if it's likely a electrical or mechanical issue.

 

Did you by chance inspect your valve lash/ valve adjustment? Were you able to check fuel pressure? Still no engine light? Are you running stock ecu? All engine grounds good? When it is idling have you done a engine balance test to see if you are maybe only having this issue the one cylinder instead of all 4. A compression and leakdown may need to be done after the first steps mentioned.