To start, I've been referred to this forum by quite a few people after posting a need help ad on craigslist.
My car 2001 C5 ZO6
Miles 36,000
Mods Magnuson supercharger
Full exhaust 3inch piping
Vararam intake
Custom tune

I've been trying to diagnose this problem for quite some time now. I got the "reduced engine power" after a hard acceleration from 1st to 2nd. Since this has happened I've:
Replaced the battery
Cleaned the chassis grounds
Replaced the the Throttle Position Sensor
Inspected the wire harnesses
Inspected the PCM (connections)
Inspected the TAC Module (connections)
Inspected all fuses
Inspected under the dash for loose wires to the pedal assembly
Inspected and cleaned the throttle assembly
Cleared and reset the PCM with a scan tool

These are the codes that still come up: P1516, P1220, P1120, P1518, P1120, P1220, P1516. These are the codes that the scan tool extracted in this order and Yes, some of them repeated themselves. 7 codes total.

My next coarse of action is to replace the TAC Module. Upon inspection I noticed it rattles. Something is loose inside the module. Is this normal? Should I check something else before I replace the TAC Module? I'm almost ready to throw in the towel! This is getting extremely frustrating. I need your guys advice/expertise!!!!!!!

 

i got that also after i had to push-start my c5 cuz the battery died, waiting to hear what other people have to say!

 

this happend to me once in my z06... it happen the day after i came from the track.. i was told it was cause i didnt put my filter back on, that the vararam sucked in something... i put it back on and havent gotten the code since...but in my h/c c5 i got it once when the battery was weak. i turned the car off & on. i also replaced the battery and messeage hasnt come back on

 

i am considering replacing the battery, probably will next week or somethin

 

I had the same problem. I ended up replacing alot of stuff like you have when it was a wire that ended up being pinched behind the intake against the firewall. Hope you can find the problem.

 

The TAC module should NOT rattle and that can and will give you reduced power issues. Contact Gene Culley at www.gmpartshouse.com for the BEST deal on a new module.

BC