nice explanation tech. but i am guessing your egr is just stuck open or closed. from my experiences w/ my egr on my carbed rig, if its clogged, you will get pinging upon acceleration. so i dont think its stuck closed but try tapping it w/ a wrench or small hammer to see if it does anything.

87 22R PU, 2? body lift, 33? BFG muds, 4.88's, F&R Lock-Rights, Rancho Shocks, EB's Street RV Head w/ 268 Cam, LCE Header, 2" to 2 1/4" exhaust, Flowmaster 50 series, Magnaflow high flow cat, complete Herculined SR5 interior, V6 BB, MC, and calipers.