I've had a couple issues with my truck recently and I was wondering if someone could give me their opinion of what's wrong with my 5.4.
My truck misfires with a horrific screeching sound about 1/30 of the times I turn it over. I've smelt rotten egg type smells from my exhaust, and my shift points are off.
I was thinking part of it is bad coils, and the rest of the issue revolves around running rich from my throttle body spacer, intake and exhaust.
Opinions? thanks!

 

Those mods on the engine without a programmer will make it run lean, not rich. Rotten egg smell would indicate fouled cats, and misfires will do exactly that.

If it's misfiring, there should be codes stored in the PCM. Read or get the codes read, take care of the msifires, and move on from there. Eventually the misfires will destroy the cats from dumping raw fuel into them.

 

Sounds like, or smels like, bat CAT. I have read that bad cat conv. Can cause truck to run bad. But cat should not go out unless you are at really high miles, or something else is wrong, usually running rich makes cat workover time.

 

Yup, postal said it well. I had misfires and ended up with flat cam and a broken rocker, was worried cat might have gone out to.