I have a 94 Chevy Silverado 2500 series with 350 eng & 4L60E AT tranny. I was pulling my trailer and it's been plaguing for weeks now. It seems like it doesn't want to shift. I can't tell if the motor isn't getting enough RPMs for the trans to shift or if it's a trans problem. But I was coming up a hill and the truck wouldn't shift, I let up on the gas and heard a LOUD BANG! I looked in the rear view mirror and saw a BIG CLOUD of Gray smoke about 1/4 mile long! Then the truck shifted and seemed to run better! I brought it home and you can see gray sediment in the exhaust pipe. I haven't driven it since, I'm afraid I'll get stuck with it somewhere. Anyone have any idea what's going on here? I would appreciate any help!
Thanks!

 

start the truck and see what happens. maybe let it run and hit the gas every so often to see what happens there. do you know what you were taching when it popped?

 

I ran the truck yesterday and it seemed ok-shifted and no more plaguing. What's going on here?? I am worried to get stuck with it, but can't diagnose it myself because there's no service engine light on. Anyone have any ideas what the problem could be?

 

Im thinking catalytic converter, nothing from the tranny is going to be in the exhaust system

 

Well, I took it to the garage and they did a back pressure test on the exhaust- in2pro was right-bad cat. It blew out the manifold gasket. So got it changed and got full tune up for it. Hopefully it will run like a top now.
Thanks for the help!