I have a '94 Chevy Silverado. When I bought it, it had a bad motor in it. I got a used 350motor from the junkyard. It is automatic. When I step on the gas, it hesitates, sometimes it bogs out & seems like it's going to shut off. So I let off the gas & give it gas again-it hesitates. It seems to idle fine. And sometimes when I'm coasting at a lower speed & I'm not on the gas, when I do step on the gas lightly it will buck until I let off the gas or step on it harder. Any ideas on what could be the problem?
Thanks!

 

I'm really just guessing.But I'll try to make them good guesses.I think it could be a cylinder running bad in the engine,so I would check the spark plug,and spark plug wires,then maybe the distributor.Or maybe it could be the EGR valve.I've seen and felt what you're explaining.Most the ones I've see have been dead cylinders though.Hope this helps a little bit.

 

Check fuel regualtor, tp sensor, crank sensor. Sounds like too much gas is being dumped into the engine or there is not enough spark. A 94 and back GM will not throw lights as easily as the newer trucks, so trial an error might be the only option besides going to a garage. Is that motor a Vortec?
If it runs good at idle and full throttle then try this.

Try these things:

1. Check fuel pressure. Might need to look up what pressure your truck needs.
2. Check plugs and plug gap. Make sure they are firing.
3. Check wires for arcing.
4. Check Coil.
5. Check the timing! This could very well cause the symptoms you are describing.

 

Outcastz89

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Haha,those are pretty good.I like the first dodge one about the best,the hemi one made me laugh quite a bit too.The other ones are pretty good too.

 

Did you find a reason why it was doing this? I am having this current issue. The exact same thing. Please let me know. I know this thread is old but thank you