My brother owns a 94 S-10 blazer with about 170k miles on it. Yes, I know these things are very problematic but thats why we're trying to sell it. Anyway, about 4 months ago his SES light came on and when I did the diagnostic check it came out as an EGR problem. So I pulled off the EGR valve and cleaned it out real good and sprayed some carb cleaner in it (don't worrry this the electronically controlled kind so there is no rubber diaphram to worry about). Then I put it all back together and it ran fine. Today he gets home and says the SES light came on and it instantly began to idle poorly. Did the diagnostic check and low and behold, its the EGR again. So I pulled off the intake plenum and took out the EGR valve. It still looks fairly clean and the little valve end with the torx bit hole moves back and forth smoothly. So my question is: How do I know if it needs a brand new valve or not? And is there a way to fix it because these things cost a fortune? I don't see how these things can go bad being that its just an electronic solenoid and no diaphram to worry about. -On another note, does oil circulate between the intake plenum and intake manifold? Because there is oil residue all over there. Might have some leaky intake bolts and/or gaskets. Thanks in advance for the help.