GMC Repair: 1994 Chev Blazer, egr valves, engine temp

Question
I have a 1994 Chev Blazer 4x4 with the standard fuel injected 6 cyl, auto trans.  Just recently the vehicle very rough idles when cold until engine temp  reaches 210 then after shuting off the engine and restarting, it works fine.  The "service engine soon" amber light is on during rough idle and then off when all is well.  I have not run a code check as of yet. I have checked all fluid levels and all are well.

It will be going to repair soon, but I was wondering if there were any simple items to check before going in?

Thanks,
Steve

Answer
Hi Steve. I really need to know the codes before I can give you an answer to this question. I have had many many many problems with EGR valves sticking open on these vehicles and replacing the valve is only a temporary repair. Try tapping on the EGR valve when the engine is running rough and see if it smoothes out. This is certainly not a 100% test, but if it does smooth out, then you have your answer. Please get back to me if this is the problem and i will tell you the permanent cure for this problem. Manfred