1998 Chevy Truck

Sounds like you went overboard on trying to fix a misfire. The most important thing is compression. And that needs to be tested. You may have a dead cylinder. Get a compression test on ALL cylinders, and let us know the results. We can certainly guide you from there.

Misfires are caused by many things. If you've done a valave job then i'd suspect that it was missing and you did this before checking anything. This can be anything from a plugged fuel filter to a bad injector. I would suspect that it's an injector or the injector lines under the manifold. It's best to have apro check these as it can get exspensive to fix this area of the truck. It can also be a vacuum leak which you can check with choke cleaner. Spray it around all the areas of the intake where it mates up ot the head, if the idle changes either up or down then you've found the leak.

I wold doubt it's cam wear as that cam is billet steel. Maybe a bad lifter or bent pushrod, but you would have seen the pushrod thing when you tore it apart. Also checking in the manual available to us there has been alot of problems with poor distributor caps causing this problem as well as valve guides causing sticky valves. I am assuming on the valve job that was done that the guides were checked. There was also one or two that had a catalytic converter plugged as well, but if you put a vacuum gauge on the intake if you can find one you should have about 20"of vacuum if it's around 15 then i'd disconnect the converter to see if it cures it temporarily unntil you can fix the converter. The cure for the dist cap was to get OEM. That should be easy to find, especially if you have already elimnated practically everything else. One other thing I forgot about is to check the harness going into the intake, it may h ave a bad wire or connection causing this as well.