We bought a used 2000 Excursion & have had 1 issue after the next. The current problem is the engine cranks but will not start. We had recently replaced the catalytic converter & while drivimg the vehicle started jerking. Then wouldn't start back up after turning it off. Later that day it started & we got it home. We found some frayed wires & fixed them. Now, it won't start period. The theft light is not flashing rapidly. Is the pcm bad?

 

There are several reasons for a vehicle engine not to start and a bad PCM could be one of them,,,but there are other less expensive and more common reasons for a no start.
Since we need to start somewhere some questions may help.
Did you just purchase fuel prior to the vehicle acting up and shutting off ?
Can you provide some background as to what was done maintenance wise other than the converter?

 

Replaced motor mounts since one collapsed. It was running fine for a week, then started getting the sputter. Had a new cat put in but still could hear a slight roughness. That is when the truck died. Left it alone for a while then tried again. It started back up so I was able to get it home. Read codes (can't remember the numbers) but ended up replacing camshaft and crankshaft sensors since I was getting a code for those. Found sensor wires on o2 sensor that were frayed from the motor mount failing. Patched it up but I think that is what did the pcm in. I have pressure and fuel at the rail but not getting any spark at all. That is why I believe the pcm is done in. Is there anything I can do as a shade tree mechanic to verify or something else im missing. I did find three 30a fuses relating to auxiliary power outlets that blew if that helps diagnosis.