95 Still Rough/Hunting IDLE

[mxboy349]

95 4.0 4wd manual, I am the original owner. On Start up the idle will rev up to 1500-2000rpm then settle down to 1000, then drop to 700-800 and idle like it has a cam and will almost die if I don't give it some gas. Drives fine, full power, but when stopping in neutral at a stop like the idle goes up to 1500-2000rpm and I have to give it gas to get it to come down, almost like it's stuck on the choke if it was carbureted. It does seem to get worse as the engine gets up to temperature, but this will start happening before it does. Exhaust smells more like exhaust than I think it should and it seems to get crappy gas mileage but I have checked that with numbers yet.

Here is a list of things I have checked or replaced

• Fuel Pressure - holds even at 30psi when idling, even during the high/low rpm. Holds pressure when off and it's at 40psi with the regulator unplugged.
• Checked for vac leaks just about everywhere and everything seems tight. Sprayed Carb cleaner around the manifold and other places.
• Checked function of EGR with vac pump
• Replaced PCV and checked hose.
• Replaced MAF
• Replaced DPFE
• Replaced IAC
• Replaced Temp sender
• Replaced Fuel filter
• Replaced Coil Pack, Plugs and Wires

Currently it shows a P0171 and P0174 Code but I am not sure if that is from me unplugging vac lines to get it to behave differently.

I have read about manifold gaskets and really don't want to tear into that if I have overlooked something. Any suggestions?

 

[franklin2]

Have you cleaned the throttle body butterfly? I would also try making a temp gasket to block off the EGR. It sometimes gets pieces of carbon stuck in it and that will not let it close all the way, making a continuous vacuum leak, even though it seems to work otherwise.

 

[mxboy349]

Tried removing EGR value and tube from exhaust manifold and Intake pretty much fell apart they were so rusty. Patched up the intake pipe with high temp epoxy. Couldn't get the fitting lose on the exhaust manifold and gave up before I tore up something else. Long story short, EGR system is removed and truck runs great.