Weirdest Truck Problem Yet

[jsmith10000]

Hi all. Im new around this forum but I am seriously at the point to where I have no idea what is wrong with my truck and need the help of other brains. I drive a 1988 GMC C1500 350 4x2 with a 700r4 tranny and I have the oddest issue I have ever seen on one of these trucks. The truck runs perrty good for the most part. Set aside the occasional searching high idle and always throwing me code 44's (Lean Mixture) it usually idles normally around 500 to 700rpm; however, the weird issue that im having is that, after the massive snow storm back at the beginning of February as some of y'all might recall with great hatred, the cruise on my truck has stopped working properly. The moment I engage cruise at any speed now it immediately starts to surge, spit, sputter, back fire, and just goes plain crazy. You would think something would be wrong with a sensor somewhere but the odd thing is the truck runs no different than before so when I check sensors and for vacuum leaks I dont find anything. I am at a loss. So by any chance would anyone have any ideas as to what it may or might be? Thanks a bunch.

[AirForceAngler]

Given the other issues you say you're having with this truck, I'd start checking for a vacuum leak first. That will create idling issues and lean running issues. Not sure if the cruise still worked off of vacuum in 88 or not. They used to before they went all electronic.

[jsmith10000]

Yea this truck uses an all electronic cruise. Its a black module just above the brake booster on the drivers side firewall.

[Gone Again]

Check the throttle body to intake gasket. They were a common problem on these. Spray a little carb cleaner at base of TB and if that's the problem your idle will improve momentarilly.

[jsmith10000]

Well I discovered another oddity. When I disconnected and plugged up the hose between the EGR Valve and EGR Valve Solenoid. The cruise control starts working but it still has a problem stumbling while accelerating with cruise but holds a cruise speed normally now. Also the truck idles and runs better without the EGR and it no longer hesitates upon normal acceleration so I'm going to delete the EGR system to help aleviate some vacuum leak possibilities. Just for extra info I did replace the EGR valve in a previous attemp to solve idling issues to no avail so the EGR valve isnt bad.