What would cause cylinders 1&4, 6&7 to miss and cylinders 2&3, 5&8 to work fine? The spark plugs and wires have been replaced along with cam sensor, crank sensor, coil packs and fuel filter.

 

injectors clogged perhaps....intake manifold leak.....bad gas? lots of possibilities..

have you checked for codes?

 

checked all that, no clogged injecters...no manifold leak...no bad gas. When I checked the codes it pop up IAC sensor high input. I have cleaned the MAF and it didnt help and replaced the brain but still nothing. I guess I can go with what the code said but I have been replacing parts and I would like to find out what is wrong so im not putting all my money in this truck and it still not work. So if you can help I would appreciate it, thanks

 

clean the IAC and lubricate the piston inside of it...

check my other posts regarding IAC cleaning procedures....it might help

a stuck IAC can cause it to run rough......until engine warms up...then it will run better...

is this the symptom you have??

 

To check the IAC, remove the unit from intake, with the wires connected turn the key to the "on" position without starting the engine, the IAC piston should move in or out slightly....sealing the bypass.

if its stuck....cleaning procedure it to spray it with carb cleaner to remove black carbon deposits....use a screwdriver and GENTLY manipulate the piston inside the bore until it moves....lube it with WD-40 or something similer...and the recheck it to make sure you have freed it up.....


IAC pistons get stuck when a bunch of carbon builds up in the bore/on the piston....