GM-GMC: Miss in the 1992 Sierra, timing chain, egr valve

Question
Hello. I replaced the distributor with a brand new assembly. It literally fixed nothing! I need help, most places tell me the truck is so old that all of the testing equipment is gone. The truck misses and sometimes dies at idle and in midrange rpms. I dont care if I have to throw parts at it. Please help! Oh, and could it be the timing chain?

Answer
You can start by testing a few things.  I assume you set the timing properly after replacing the distributor, if the timing stays and doesn't move around after you set it your timing chain is likely alright.  Aside from that, you should check your fuel pressure.  Another thing to check is that your EGR valve is not stuck open slightly, it can cause some strange running problems.  Try looking into those couple things and see what you come up with.
Hope this helps