Just replaced cylinder heads that cracked. Had to get new heads. Replaced plugs at the same time. Did not replace wires, distributor cap or rotor. Only misfires on #6, as it happens that was a rocker arm bolt that was hard to tighten. Didn't replace rocker arms or push rods. I need to figure this thing out right the first time very low on money as I am living on a VA pension. Very limited income, this will have to come out of food money. Tried getting one of those light up spark plug testers, it wouldn't fit in the plug wire. Also oil level is remaining constant so I don't think it is the plenum gasket. I am open to any and all suggestions.

PS. Truck ran well 3 days before getting P0306 code. Only did short trips prior to having to go 30 miles for a doctors appointment. Ran well on the way there and acted up on the way back.

 

i would guess that something in the valve train has worked loose over the 3 days, and finally come apart. maybe rocker, maybe push rod.

was the rocker bolt problem on #6?

pull the valve cover off that side, maybe remove plugs to allow engine to turn easier by hand. rotate engine and see what's wrong.

 

OK, so NONE of the basics were replaced right? So troubleshooting cheaply don't matter. Just an fyi, but the most likely reason the heads were cracked is because the cat is clogged. And the culprit can be found by reading the plenum sticky. Hate to sound like a broken record as usual, but, I'd say that's the prob. Or at the very least , needs to be verified.

 

yes the rocker bolt problem was on #6.

Thanks for the idea.

 

Forgot to mention the heads cracked due to overheating from the water pump that went out. I am sorry I left out information but I didn't think that was vital. Thanks for the help.