Chevrolet Repair: 1988 GMC 5.7 TBI stumbles, runs rough, spark plug wires, intake manifold gasket

Question
Have a 1988 GMC 5.7 TBI that I recently replaced the intake manifold gasket on, due to an overheating incident that occurred when my heater core ruptured.  Replaced the EGR valve, cap and rotor as well.  Now engine has a hesitation upon initial acceleration, and seems to run rough when going 25-40 mph with the engine largely unloaded (level driving).  I wasn't able to check the timing when I replaced the distributor, but I think it's close. Could this be causing the symptoms I described, or could it be something else.  I also rebuilt the TBI unit recently.

Answer
Hi Chris, the timing would have to be way off to cause anything like that and you would have other problmes too. The new EGR valve might be the problem if it's not a gm valve. The spark plug wires can also cause this type of problem.

Hope this helps and I'm sorry I don't have more for you to check.

Have a Great Day       Mark