Roughish Idle

So, I am back to the section of this site where it all began with a bit more knowledge.

Before I start I wanted to thank everyone who has helped me thus far. No way I would still have the car without the help from the LGT community.

Now to the question.. Since I last posted in this section, I've installed an AEM wideband and a Short RAM intake utilizing the stock snorkel similar to cobb's set up (MAF has been scaled to +/- 4% learning). I still need to replace the catless uppipe I previously installed because it will not seal properly, but that is not related to my current 'issue' (if anybody has a catless uppipe that actually fits HMU). I've also reflashed the car to the AW2C522N Manual rom for improved tuning support and SD.

Since the car was purchased, there has been a slight bump at the idle. There's no certain pattern or time in which its better or worse it just kind of comes and goes. At first I thought it could be some cylinder roughness or knock, but, romraider showes no indication of said events. It would also be assumed it could be a leak, but seeing as the learning values usally stay around the +/-4% range at idle, I dont think its related to that either. Only sort of indication I see is that my wideband will read around 14.0 instead of the target 14.2 when the bump gets most noticeable. Therefore, I assume its related to fueling seeing as the ECU isnt trying hard to get it back to the 14.2 seening as learning values stay the same.

One possibility is that I have an injector partially stuck open at all times creating a richer than ideal AFR causing the bump. I have noticed when I reset the ECU and clear the learned fueling parameters the AFR will drop way down sometimes into the 10's and then rise back up when the ECU decides to correct it. Also when I reflash the car, before the IAM is at 1, if I tap the throttle the engine will bog down a whole lot almost to the point of stalling as the AFR gets super rich on the wideband. This also occurs (not as bad) when the car is cold and it rolls to a stop.

Another idea is it is something to do with the timing belt, idle air control valve, or spark plug and coil system. The bump is a little more noticable when it is hot outside and I sometimes get an interal sounding knock which could just be the timing belt tensioner or piston slap (less likely). Definitley not rod knock though.

This isnt a real pressing issue as my car is pretty clean as far as knock and missfiring is concerned at this point. Just kind of annoying and makes the ride less pleasant.

Wanted to see what you guys thought or if anybody has any experience with a similar issue.