OK sorry for this being so long but I feel it necessary. 3 weeks ago I did Pacesetter LT's(ceramic coated), removed cats, mandrel 2.5" all around,Magnaflow dual in/dual out single stainless muffler,and LT1 fans. I had a number of exhaust leaks but fixed them all and even put Nitrogen through the system to make sure. The next day I started to get a terribly rough idle-it would go to 3k and back down and repeat untill it ran for about 5 minutes then it would start to load up. When scanning I wasnt getting consistent o2 readings so I replaced both front 02's(obviously the rears are gone and turned off) and they were both totally clogged so it was needed. Well since I got the new o2's(stock ones) it has gotten worse. It feels like when your driving with 7 spark plugs except worse-it bogs and loads up and sounds like I have a flat tire! But I can drop it in 2nd(automatic) and get it in higher rpms for a few seconds and it clears up. I can but it back in drive and most of the time it clears it up and drives fine. Then the next time I crank it up sometimes it will be better sometime it wont. Each morning though this is the case. Through this whole ordeal I have been tuning hoping I can fix it. I have tried in speed desnsity and MAF. At times we would flash it and it would be fine then start back up sometimes in minutes other times hours. We thought I may of had a corrupt file but I put my the tune in I had before the headers(that I had no issues with before) and it didnt help. Ive read about you F-bod guys having issues with your o2's heating up after LT's and I dont know if these sound like problems from that. I have a stock MAF but it is descreened(for over year now). COuld this be a factor? The only code Im getting now is a P0200(injector circuit malfunction). Please help Im running out of ideas! My mods in the sig a current! Thanks!

 

Could be one of several issues. LT's are known to cause a rich condition at idle, and sometimes lean at cruising. You need to put that puppy on a scanner and see where your LTFT's are.
Another thing to check is all the wiring connections topside. Make sure all the coil/injector harnesses are plugged in right/tight. The P0200 could relate to either one, or a short to ground, from what I understand. Might make sure you're getting the full 5V signal from the pcm.

 

Yeah I would just start with checking to make sure everything is plugged in and the plugs and wires are good. Thats if you have not done all that already.

 

I think you would get a better response if you posted this is the PCM Diagnostics & Tuning section.

 

Obviously I had to adjust my LTFT's after the exhaust leak fix,and then after the o2 sensor fix but now they are fine except when it starts to load up/surge(whatever you want to call it) and when that happens it shows that Im running out of gas. So my LTFT's are fine except when it loads up. For a second we thought I was running out of injector but it doesnt match up. Ill post this in the PCm section too! Thanks!