I own a 1999 Tahoe with a 5.7L with 100,000 miles on it. I have been experiencing a misfire after the engine gets up to operating temperature. I then took it to the local Chevrolet Dealership for a tune-up and made them aware of the misfire. They completed the tune up, check the OBD and found no codes and said that they road tested it and could not get it to misfire. I can really tell the misfire when pulling a car trailer. The exhaust echos off of the trailer and it can be heard quite clearly. The misfire could be heard through the right tailpipe. The Tahoe has true dual exhaust. Items that have been replaced during the tune-up and afterwards: distributor cap, rotor, coil, plugs, plug wires, fuel filter, air filter, battery and intake gaskets. I did a compression check and All cylinders are 115 to 120. I even took the truck to the muffler shop to check and see if it could be a baffle in the mufflers...NOT...they did put a balancing tube in the exhaust so now the misfire can be heard in both tailpipes. The power does drop off a little during misfires. I think that about covers it. Any suggestions would be greatly appreciated.

 

I might be way off, but maybe the ignition control module?

 

THEY HAVE HAD PROBLEMS WITH LEAKING INTAKE GASKETS... MIGHT CHECK