Going insane!!

Any and all help is greatly appreciated!
I've got a 94 C1500 auto with a 4.3.
Started the truck up in the am.
It ran fine for a few min., stuttered and stalled.
I had to go full throttle to get it started. Got it started and had no power.
Got to work and the right ex. manifold flange gasket was blown out and the manifolds were glowing.
I found the converter busted up.
Gutted the cat and cleared out the piece in the intermediate pipe.
Fired up the truck and it seemed to idle ok.
Drove the thing home and no power with both manifolds glowing.
At idle all parameters on scanner seem normal except a/f ratio showing 0.0, but O2 crosscounts ok and fuel trim about 128-134.
fuel pressure ok, new cap, rotor, plugs and coil. changed out ign module.
compression ok .
Truck is dumping fuel into engine, no throttle response, no power and sometimes it will backfire out intake.
Possible pcm?
This thing is driving me nuts!!!

I would check the fuel pressure maybe a defective pressure regulator.
Pull plugs and look for a heavily soot covered plug maybe a leaking injector.
Cracks around the exhaust manifold will make the computer think the engine is running lean.

What was the engine temp? What is the MAP reading? Like rhandwor said, exhaust leaks can cause a lean condition and the ECM will add fuel thinking it is running lean. a/f ratio showing as 0 is not right. Are you sure 02s are working right?

//2000CAYukon

temp was about 183 degrees and map was around 17".
single o2 and it seemed to be switching mv. high to low.

I would check the fuel pressure maybe a defective pressure regulator.
Pull plugs and look for a heavily soot covered plug maybe a leaking injector.
Cracks around the exhaust manifold will make the computer think the engine is running lean.

My 88 was running rich and thought my flange gasket was bad cause it was loud in that area but its been too damn cold to do anything until this weekend when I popped the hood to check fluids and noticed the 2 rear bolts of the exhaust manifold were completely gone. I noticed the gasket just hanging there. I thought they might have broke off but got 2 bolts and they went in perfectly fine.
Not sure how the heck they came out or when but took care of the rich smell. I would've never guessed That would've been the problem. That was my next job to tackle. Well that and the tranny. You guys have'nt let me down yet and wanted to thank you for all the help I've gotten here. You guys are brilliant and with the desire to help others Who can beat that!
I posted a question in the "ehem" Dodge section for help with my fathers car and got absolutely NO response. I'll forever be a Chevy man. Thanks again!!!