i think it is your spyder injector. egr will affect idel but if you get on the gas it should run even if the egr was completly broken (al be it maybe not the best) the large ammount of carbon build up on the drives side is a tell tale sign of spyder problems. run a search on the form for the spyder injector youll see what to do and the signs, that way you can see if it matches up. it soulds like fuel is getting to the spyder because you said you had good pressure i just dont think it is getting to the cylenders.

 

Sounds like it could be the poppets on the spider assembly but what threw me off is he told me in an e-mail that he found a bent pin on the EGR and repaired it. Then he started it up and after a while P0122 and P1406 came back on him. He cleared them and as far as I know they haven't come back yet but something threw them. I've dealt with poppets on a couple of engines and they threw P0300 series codes which he's not getting (at least yet). They feel like a miss all the way through the pedal. Would the spider assembly cause P0122 and P1406 ? I suppose it is also possible that these are two different problems. I had sticky poppets on a 1994 Safari (OBD 1) and it didn't throw codes for quite a while because it would come and go.
BTW, unofficialy, some engineers I know did some tests and found the best fuel additive to clean up poppets was Chevron with Techron.STP and some of the other brands did't work as well. It used to work on the Safari if I caught it early enough.

 

Fuel injector cleaner will never be a fix for any noticable problem. It should be used as a preventative maintenance. In my experience, Chevron w/ Techron has been the best all around fuel system cleaner and worked great on my grandfather's old S10 2.8L TBI.

To check for a leaky spider, pull off the MTV on the top of the intake plenum under the plastic cover and have a look inside. If you see fuel pooled on the lower intake, then you've got a leak internal to the plenum. There are a few sources: internal fuel lines, faulty o-rings and/or a faulty FPR.

If you are getting a miss due to leaky poppet nozzles resulting in uneven fuel distribution, then you would have to pulse the injector with the poppet nozzles out of their bores and inspect the fuel spray pattern. This would require that the fuel pump be engergized and that you had something to capture the fuel that will spray out. Also, the upper plenum would need to be removed to do this check.

 

Sorry, wasn't trying to imply that it was. GM document ID 1234172 explains the proper procedure. It was just a tip for keeping them clean once you get it fixed.

 

Thanks for all the input, guys. Still can't figure it out. Doesn't seem to be any type of leak once i open up and get inside the plenum after having done the regulator. seems the same as after i cleaned it. I think my next guess is gonna be fuel pump. When i get it running, it runs like crap all around. When i hit the gas, it actually goes down in RPM before up. and the idle is so eratic, it's undriveable. i know the pressure seemed fine when i checked it, but i caught it not engaging the other day when i turned the ignition on. 3 times in a row, and then more sporadically. surprisingly the truck still started and ran, but if it's coming and going it could explain a lot. i think the relay is ok, seemed like it was clicking every time regardless of pump engaging or not. Wish me luck, and if anybody has better ideas, i'm open in case this don't work!

 

SURE DO wish people would post these outcomes