I recently had my original carb for my 83 z28 rebuilt and put back on, along with the o2 sensor and tempeture sensor. Ever since then my car has been hesitating like crazy! When I am stopped and I slowly push on the gas the car just sits there and then I have to push harder to get it to move, it seems perfectly okay on the highway though. I've been told that it's not burning the fuel right which could be caused by a number of things like spark plugs right? I took it to a mechanic and they looked at it about 2 weeks ago and told me that it doesn't need a tune up. I don't know what is wrong for sure but I don't want to dish out 70 bucks just for someone to diagnose my problem. Any ideas?

 

Maybe its your fuel pump?

 

About the only possibility of a fuel pump causing a low engine speed problem that goes away at high engine speed is excessive pressure causing flooding - not very likely.

Most "carb" problems are caused by the ignition. However, since this problem came up after the carb rebuild (why did you have it rebuilt?), the carb sounds suspect.

Does this exhibit itself under all conditions - cold, warmed up, inbetween? Or, just when warm? Or just when cold?

 

did they replace the rods and hangars (hangers? sp?) in the Q-jet when they rebuilt it? If so, did they use the same style, or did they try to "tune" it?

 

They replaced everything on it and didn't tune it. The guy that did it was really smart and explained a lot about how it COULDN'T be tuned that it should be left original.
The carb was rebuilt because the spring to the butterfly flap thing was broken and something that holds the fuel was broken. I wish I remembered the names to this stuff lol. The hesitation happens whatever temp it is. This didn't happen before we replaced the carb, temp sensor and o2 sensor. It might be anything else though....the car is 21 years old lol.