Re: How to check if EGR valve is working ?
A maf can give your symtoms on a 2.4, but if you have a 1.9 its likely to be egr.
Cap it off properly both ends and disconnect and plug the vac pipe that operates the butterfly on the throttle body.
Why anyone would want to put half burnt fumes back into the engine I don't know, all it will do is clogg it up, as you are finding out.
EGr is great on new cars, when it works, when they get older its nothing but a p.i.t.a and best off being removed.
Thats just my opinion though!