EGR valve problem

[f.monroe]

I know there are several different egr valves . Does anyone know the gm part number for the correct one for an 87 3/4 ton with a 350 . MY 87 is stumbling off idle and I looked at it tonight . The EGR opens as soon as the throttle is opened . The solenoid that controls it is apparently working since the egr doesnt open with the wiring unplugged from the vac solenoid . Anyone have any experience with this problem . I need to make sure that it has the correct egr first . i know that some open with vac and some close . I think the one on it now has 17087185 as a part number . Just for grins I unplugged the egr and it has way more power . Spins the tires (33x12.50x16.5)from a dead stop and it didnt do that before . It also seemed to cruise 65 with ease and it has always felt like I was pushing it . I always thought it was the 4.10's in the rear . Frank