Failed for high HC at 15 mph, max is 96, ave 36, meas 99. Tech says something is open. Followed all steps from FSM, no faults. EGR was filthy!! Got a lot of gunk out then I slapped it back on. I tested the EGR valve, at idle I apply direct vacuum it misfires and wants to die, good. did the test with 3 way union at 3500 rpm and 3000 rpm with R port vac line from modulator connected to intake vac port, pass. However, with the engine off, if I apply direct vac to the EGR valve it doesnt hold 10 inches of pressure like it's suppose to for 20 sec min, hell it doesnt hold any at all. My question is, does this mean it is stuck open slightly and causing exhaust to seep thru to the intake causing the abnormally ppm level of HC??? Because he also said the idle is low. I dont know how else to clean the thing or will I have to surrender and fork out 150 bucs. Truck runs great, but I guess it could be better and mpgs could be better. Please help