Truck running funny! HELP!?

sounds like engine is skipping. when is the last time you had a tune up? if engine skips badly, the rpm's drop and that will cause your knock. that would be the first thing to do is a tune up. Next would be coils if they are coil over plugs and not wires. Use motorcraft plugs to do tune up. If problem still there then take to shop to pinpoint coil.

Yeah. When was the last time you checked your coolant? Have you had to add any recently?

No, unless your car was overheating, it being low would not but I would fill it. It could be a clue though if you have lost that much in a shot period of time? When did you check in last when it was above the min line?

The Rick is also going on you have checked all of this or would think about looking at this. Unfotually those who ask questions on here are not mechanics or techs, and would not think about looking at this. I am a tech.

I am going at a head gasket. Does not become noticeable until the engine is hot and the thermostat opens. Would explain why it is intermittent.

So have you lost a lot of coolant, had overheating problems, or had water or a lot of steam coming out of the exhaust pipe? Does it start acting up after the engine is hot or is it completely random when I does it?

No, low coolant has nothing to do with your truck's engine performance unless your truck doesn't have any coolant in both radiator and overflow tanks. But with your engine, it seems like your emission control plugs are defective. Check to make sure if they're not good by running the engine and then touching the emission plugs with a screwdriver. If the engine jumps then that's the problem. Or, if the emission control plugs box is not the problem, then most likely it's the transmission or transaxle.

Hey Rotten! I think ATF is thinking blown head gasket, could be,

You didn't mention white smoke out exhaust or oil in coolant or that the oil looks like mocha coffee?

Now, does this piston going crazy business sound like a standard transmission trying to take off in 4/5 gear? Some transmissions have

an electronic overdrive that will stay engaged when you come to a stop which sounds like what you might have? Oh! By the way, you should correct Maintenance issues ASAP!

Or You need to Diagnosis!

I'd recommend starting simple, possible vacumn leak? take a spray bottle and spray around your intake and vacumn hoses and listen for rpm to increase or stuttering to go away.

then move to fuel, Esp. fuel filter,injectors, or ECM?

And don't forget Ignition: spark plugs, wires, coil/module or again ECM.

Happy hunting

Get a CarMD. I use this to tell what's wrong with my car. It's very reliable especially if you don't want to go to the mechanic and get a diganostic check, as it is very expensive.

www.carmd.com

Check it out. I hope this helps.

Dirty intake, dirt in the exhaust, get it checked.