My 95 went into the "Turkey Jerkey" mode as I returned home from a day of fishing. I knew from the great info. I've found here what the probable cause was and decided to remove the EGR valve to check it out. (what a pain!) Anyway, while I was going about the task of removing the grain of carbon that I found keeping the pintle (sp?) valve open I began to wonder "what if"?
Here is that question: What would happen if instead of using a gasket with holes in it a solid flat plate was used to prevent exhaust gas from mixing with fresh air to prevent carbon contamination. This leads to another question: What activities does the EGR valve perform aside from mixing exhaust gases with intake air? Does it monitor air / exhaust flow that involves a closed loop communication with the truck's computer to make adjustments on the fly or is it a dum system that responds to cycle requests passed on by the throttle or vacuum load? We don't have exhaust tests where I live in Va. so if my blocked EGR port caused a bit more unburned exhaust I don't see a problem unless it just created a whole host of other CEL's or problems. Just thinking out-loud here...Thoughts?

 

EGR systems are used to reduce combustion temperatures while cruising to reduce the formulation of NOx, improving emissions. Most of the time, when an EGR system is disabled through a tune, the fuel mixture is made more rich in those instances that the EGR would be operating resulting in reduced combustion temps at the expense of more fuel & emissions.

Depending on what your truck has for an ECU/PCM setup (there were three different configurations throughout 1995 production), it may monitor the EGR valve performance. I am fairly certain that the OBD1 & OBD1.5 setups do not and do not know for sure that the OBD2 setup used in this year did. One way to find out is to do as you noted and block it off and see what happens.