off idle misfire

[flivesay]

I found the thread below but have not seen a resolution. Anyone ever find the solution or offer one up? I have replaced almost everything and have not determined the problem. It is exactly like the following description--

Originally Posted by oper8or
My GMC half ton v6, stick, 2 wheel drive, has a misfire when running at a level speed. It doesn't matter what speed I am going. Though it idles smooth as silk. It has great take off and pick up. But when travelling at a level speed, it starts misfiring. The only code that comes up is "Random misfires all cylinders". I have replaced the following with no improvement; plugs, wires, cap, rotor, fuel filter, air filter,pcv. I have tried a different coil, a different distributor, cleaned the injectors, checked and double checked all connections, updated the software on the ecm. Still misfires. I took it to the best diagnostics guy in the area and I stumped him. He spent five hours on it and was at a loss except to say that there is a very slight possibility that there is wear in the timing chain and gears but he was puzzeled as to why it was idling so smooth if that was the problem. Anyone have any ideas? <HR SIZE=1>