what is EGR valve and symptoms of faulty

could someone please tell me what the egr valve is and what are the symptoms of a faulty one? My S-10 seems like it is lacking power. It is a five speed. It seems like in 3-5 it just won't perform well in the upper rpm range. I was wondering if the egr valve might have somrething to do with this?

Egr valve is an emissions componant that is used to reduce tailpipe emissions by "recycling" exhaust gas (simple laymans terms).
A valve that is stuck open will cause a rough idle or stalling problem...
A valve stuck closed can cause spark knock on acceleration or cruising
A valve that opens too much or too soon can cause a stumble, hesitation or loss of power during acceleration

thank you very much. perhaps you can answer my question about replacing a starter on my 94 s-10 that I posted one thread earlier . Thanks for your reply as my truck has some of the symptoms you just described.

forgetting emissions, what would be the effect of eliminating the system? colder air? better? not?

Hello....I owned a S-10 for about 11 years. My truck (2.5 liter, 5 speed manual) never had much power from 3rd gear on up. I did replace an EGR valve on a different car. The car would just die or have a major power loss. After the car died, it would start fine and continue on with no problem. I think the Engine light would also come on.