97 ram code p0308, did plenum pan

I have a 97 1500 sport with a 318, it was running kindda rough so i looked into it found it was throwing a p0308 code, cylinder 8 misfire. Found others misfiring as well, but not enough to throw a code. looked a little closer and researched it and found it was most likely the plenum pan gasket so i replaced it, swapped out the plugs, wires, cap, and rotar. Even ran some carbon cleaner to clean out what the burning oil left behind. It ran better than it ever ran before, but the problem came back a week later.... the code came back to. It's running rough again and at 45-60mph it bucks at low rpms but runs great at all speeds when reved up.

any help would be great!

Try here
http://www.obd-codes.com/p0308

I know that the code (p0308) is for cylinder 8 misfire. That's not the problem. :headshake I have access to a diagnostic machine. the problem is that it came back. I'm gonna do a compression test tommorow, anybody have any other suggestions?

yes perform a compression test and possibly a cylinder leak down

just go over all of the work you have done before you start chasing your tail around the truck.is number 8 the only cylinder missing now?you can always pull the plug to make sure its not cracked, or gaped wrong dare i say...I once had a number 4 misfire that came back a week later with the same code after i fixed it with a tune up.I could of started chasing my tail doing comp. tests and swapping injectors, but instead i pulled the plug only to find out i cracked it during the install with my air ratchet (never made that mistake again).remember it ran fine for a week!