Chevrolet Repair: C1500 misfire/jerking, fuel pressure gauge, intake manifold gasket

Question
I have a 98 Chevy C1500, V8, 305. I have had a general misfire code pop up intermittently over the past two years. During that time I gave it a full tune up, but the problem still occurred. Since it only occasionally gave a general misfire code I decided to wait until another symptom arose. Recently the truck has begun violently jerking/surging at speeds between 45 and 60 mph, and only after the vehicle has been driving for a while (20+ minutes). During this time the only code I get is a general misfire. I have also noticed that the converter clutch seems to engage and disengage randomly between 45 and 60 mph.

So far I have replaced the following items: cap and rotor, plugs, wires, ignition coil, fuel injector (spider) assembly, fuel filter. During the initial misfire issue I replaced the intake manifold gasket due to leaking.

It is at the shop now and they seem a little stumped. Any comments or suggestions that you can offer would be greatly appreciated. Thanks.

Answer
HI SCOTT, THE TRANSMISSION CONVERTOR COULD BE DOING THIS BECAUSE OF THE ENG SKIP..[COULD BE] NOT CERTAIN. WHEN THIS IS OCCURING HAVE YOU OR THE SHOP EVER HOOKED UP A FUEL PRESSURE GAUGE AND WATCH THE PRESSURE ??? WE HAVE HAD MANY PROBLEMS WITH THE FUEL PUMPS LACKING NOT ONLY PRESSURE BUT VOLUME AS WELL. THIS COULD CAUSE A SKIP AND JERKING.. OTHER THINGS THAT COMES TO MIND IS BECAUSE THIS HAPPENS AFTER DRIVING A WHILE IS > IGNITION MODULE ..ALSO IF YOUR SHOP CAN HOOK THIS UP TO THERE SCAN TOOL AND CK FOR FREEZE FRAME DATA THEY COULD TELL IF THIS IS A FUEL OR IGN PROBLEM..I WILL SAY THE WAY YOU HAVE DESCRIBED THIS TO ME IT SOUNDS LIKE A IGNTION PROBLEM...ONCE YOU FIND OUT IF IT IS FUEL OR IGN YOU CAN ZERO IN ON THAT..LET ME KNOW IF YOU HAVE ANY MORE INFO ON THIS.. GET BACK TO ME WHEN AND IF YOU DO..GOOD LUCK,,,TOM