94 Sierra Weak Acceleration

I have a 94 GMC 1500, 350.

THe last month I have had very weak acceleration, the power isn't what it should be. It accelerates more like a 4 banger.

I've had it at two different shops, they both say everything is fine. This is after new plugs, plug wires, cap etc.

Any suggestions? Everyone says it runs great, but I know better.

It could be that you're tranny is slipping very badly, or depending on what tranny you have, the TV cable might be too lose, and the tranny is keeping it in too high of a gear, causing poor acceleration. Another much more feasable possibility is your catylitic converter might be clogged.

One thing it does when its cold, in first gear it will just not accelerate right, however once the engine warms up it doesn't do that

Transmission shop drove it and said it is not transmission related.

Exhaust was just repalced from the converter back, they said the converter was in good shape, not clogged.

Hey,
I've seen several posts on here related to this situation, and I have an experience which may help.
My 94 Sierra also would run, but would have "nothing" upon accleration. I checked codes and replaced many electrical components in the motor, still the same problem. Then I had a buddy of mine check the fuel pressure inline at the fuel filter, and lo and behold, it was just a trickle.
So, I recommend checking your fuel pressure. If its low, That the good news.
Now, you've got to drop the gas tank to replace the fuel pump. If you cant do it yourself, you might be surprised what this may cost you. Also, in my case, this repair turned out to be a nightmare when the guy who did it for me broke the fuel sending unit when replacing the pump, so now I had no gas gauge ! Rust was a problem with the fuel lines and fittings, so you may look into replacing the whole sending unit and pump together.
Hope this helps, I know it took me 4 ever and a lotta money b4 I even tracked it down to This !! We're Truckin' Now !!
Good Luck.