Well I got around to doing some more troubleshooting and gave the EGR valve the old tap-tap-taparoo and sure enough the idle smoothed on out so I'm pretty sure it's the valve. Now should I bother taking it apart and giving it a good cleaning, or just get a new one to swap it out with?

Edit: I found some tips on cleaning one up. But if that doesn't work or if I decide to go with a new one... where's a good place to get a deal on one? Thanks.

I just pulled mine tonight and realized that it's not that dirty AND it was loose on the block. So the gasket was leaking.

I would say pull it and clean/inspect it first. Check to see if it holds a vacuum. You can see the diaphragm if you hold it upside down. Mine has 129k on it and it wasn't restricted at all. Some carbon build up but nothing some carburetor cleaner couldn't take care of.

My 89 with 130K needed a new Egr valve, it was not functioning and my mileage was terrible. The truck vibrated badly at idle, and ran pretty weak. I replaced it and viola, smooth idle. My Egr had carbon build up, I think from a leaky PCV valve grommet and stuck PCV valve, but I am guessing. Could that make sense? The timing was also pretty far advanced out of tune. I fixed things one at a time, and checked the idle, and I think the EGR was the culprit for idle vibration and power at high speed, but all combined really helped. I was told by the previos owner through a 2nd party that a tranny shop said it was shifting funny because of the EGR as well, but I didnt have it long enought before I replaced the EGR to notice.

Good site for you noobs to bookmark if you haven't already,

www.autoshop101.com Great howstuffworks site <img src="/forums/images/graemlins/kewl.gif" alt="" /> <img src="/forums/images/graemlins/kewl.gif" alt="" />

EGR Emissions #7 in the tech articles; there should be one there for the PCV as well.

I cleaned mine out pretty well last spring with a small bore gun cleaning kit. Gun solvent and the small, round wire brushes work well to get up inside the valve.

I don't know which system you have specifically, but here are some basic tests. With the engine idling, attach a vacuum pump to the EGR and apply vacuum. The engine should stumble or die.

This is the test I used to check my EGR. Sure enough the engine stumbled and started to die when applying vacuum with the pump. For some reason the top of the EGR was capped off at the end. It looked like an adapter to make the hose fit better but upon further inspection it was just a cap. Also installed a new Knock Sensor, unhooked the neg terminal for a bit while I cleaned up the shop. When I hooked it back up I took it for a drive and no CEL (was getting a code 71 and 52). Before it was coming on about a minute or two into the drive; about when i hit 20-30 mph.
I was also getting the vibration at idle, when stopped at a light or whatever and that is just about gone also.

So hopefully that problem is solved. The last tank before the fix averaged about 15 mpg. Now that these two things are fixed should my gas mileage improve? If not what to look at next?