I'm new to this, so bear with me. I have a 2001 2-door 2wd Blazer. Recently, a bad exhaust leak under the hood melted the jacket on some of the wiring harness. We carefully repaired these burnt wires. Now, the car will idle just fine for as long as you let it, but as soon as you touch the accelerator, it idles down and dies.The car will not stay running after this unless you keep a foot on the gas and keep it running.Any clues?

 

First thing with any engine performance diagnosis, is the service engine soon light on? if it is, retrieve codes and post back.
Next question, where exaclty was this exhaust leak at? Was it running perfectly fine before the repairs were made? Check that there is a good amount of airflow from the exhaust pipe, you may have a plugged exhaust and that caused your leak that melted the wires, now your exhaust has nowhere to go? Or the melted wires shorted voltage to a signal wire going back the PCM and fried something internally....

I could go on and on with possible scenarios, they're endless, start with checking codes. Cheap code readers can be had for less than the diagnostic fee would cost at most shops, if you find one problem on your own its paid for.

Good luck

 

Check EGR circuits and manifold temp

 

This was the leak. I believe this is an air pipe. The elbow became brittle over time and the side blew out of it, forcing all that hot exhaust onto the wiring harness you see in the picture. It would still run when I got to it (my wife was out in it) although missing terribly. My fear is a short in one of those many wires that were repaired or that something was damaged by all the shorting when the wires melted.