Deteriorating Idle...

[Cookie]

So I just had my car tuned for my MS3 cam. Idled great after I got it and now sometimes it seems to idle really slow at times... like 300 rpm. Its intermettent, i can nail it and then clutch and it will fall to 300 or nail it and it will stop at 900. Or just taking it easy sometimes it falls on its face while other times its stops at 900 like its supposed to. I cant find a pattern for it. It has nevert died and usually it works its way back up but its really annoying, and it seems to be getting worse, as in it has been happening more and more. I am getting a po135 bank 1 o2 sensor heating issue code... could that cause this? Is it possible the idle is deteriorating and im having some sort of computer issue? Help.

[02blkws6]

Time for new O2's.

My idle has never been perfect on startup, but got worse as my O2's were on their way out. My AFR @ idle was in the mid 11's with a rough idle at operating temps. My afr would correct itself somewhat with higher exhaust flow to keep them warm since the heaters were done. I got about 14k miles out of a set of bosch 13111 and used leaded gas occassionally and a lot of nitrous. I pulled the headers and exhaust off and am cleaning up the headers and changing to 3'' true duals.