2004 and the head gasket blew, which took out the water pump with it. We've tore it all down, cleaned all valves, rockers, etc, replaced the gaskets, injectors, plugs and wires, mass air sensor, all other sensors around the plenum, vacuum lines. No cracks in the plastic intake or vacuum leaks anywhere. Mine has no EGR valve and didn't come with one from what I understand. Anyway, it's hard to start, idles hard, runs rich. Here's the kicker. When it's revved over 1,000 rpm, it runs smooth, no vibrations to be found. When the throttle is let back down, it wants to die out completely or goes back to rough idle. The battery has been disconnected overnight so the ECM could relearn, but goes right back to the same thing. Sometimes the check engine light flashes, sometimes solid, sometimes not on at all. And today it developed a new issue. The speedometer shows the needle pegged out at 100, the gas gauge is almost upside down as well as the temp gauge. I'm beginning to think the damn thing is possessed! Where do I go from here? I'm lost.

 

Sounds like your cam retard is off to me.

 

How do I fix that?

 

Do a quick search and you will find the procedure.

 

check the fuel pressure regulator as well, a friends 5.7 was doing this with a bad regulator.

 

And the tires may be low on air

 

Figure out the codes being set. FYI disconnecting your battery doesn't reset your PCM. Maybe got that distributor in a tooth off? That will show in the codes set.