Im having some problems with my 96 gmc pickup. It has the 4.3L vortec with automatic tranny.

The problem slowly progressed from being wired hesitant shifting to a almost total loss of power.
Just before it got real bad when the rpms were brought up to around 3500+ you would start to hear some clanging noises and it would begin to bog the motor. I was close to home when it got that bad so i took it home. Now i can barely get it to 2000 rpm in neutral without having it bog down and stall out on me.

Oil was drained in motor, seemed alright, no metal filings.
Dropped tranny pan, no metal, fluid is nice and red and does not smell burnt.

Im thinking the converter is shot......are these the right symptoms? I dont want to go replacing parts for no reason.

If anyone has any ideas they'd be much appreciated.

 

I would unbolt the converter from the flexplate and start the engine. It is possible that the engine has spun a rod bearing

 

i would check the exhaust system for clogs

 

sounds like the catalytic converter is clogged up.
another thing to check would be the fuel filter, it will cause you not to be able to spin higher rpm's and would cause a spark detonation due to lack of fuel, the converter could cause a detonation in the engine due to not being able to scavenge the motor of exhaust fumes corectly.

 

Clanging noises arn't good. I've seen a broken flex plate sound like rod knock.

If you're worried about the engine and not the tranny try putting a breaker bar with a 5/8 inch socket on the crank snout and turning the engine over by hand. It should rotate with little effort after you break the knetic friction (it not moving).

A bad converter would taint the ATF with a very burnt smell. Have you done any serrious towing with your truck?