John Spina:
Just remember one thing; the chip does not make the car run badly - unless - the ECM isn't reading the chip. So, a car that runs normally, then starts to act up, doesn't have the chip to blame. Look elsewhere.
About 80% of the problems with our turbo cars boil down to ignition related issues. And of that, maybe 75% of those problems can be traced to wiring issues. Bad electrical connectors and connections, plug wires that fail, low voltage issues related to aging wiring, etc.
First thing you need to do is remove the Fan Delay Relay. This horrible-design part is the source of many electrical issues. I have seen the relay fail and kill batteries overnight MANY times, resulting in the car owner replacing the battery, alternator, cables, etc., just to find that those weren't the culprit. You don't need it. Remove it. Period.
The rest of your problems are usually sensor failures or calibration drifting, such as a defective MAF sensor or polluted oxygen sensor. The stickler is the MAF; it can go out of calibration and NOT set a code. Usually results in excessive rich condition, or bad idle. A scan tool is a must. And a box of spare parts is also a great thing to have. Scour the earth to find an original Delco coil module and MAF sensor, it'll buy you years of normal running operation.
And finally, weld the crack on the header near the No. 3 exhaust port. It's there. You have it. Fix it. That crack is the major source of rich-running engines as is sucks air during idle and fools the O2 sensor into thinking the engine is lean.
Print this post, read it before you go to bed at night, and memorize it.
