1992 K1500 Blazer 350 TBI 175k

Driving home the other dayI noticed a hesitation just as you touch the gas while in gear. In other words, if I am stoped at a light the truck idles like a champ around 700RPM real smooth. Like brandy new. As soon as i apply the gas it chokes, stumbles runs rough between 700 - 1000RPM's and the smooths out over 1000RPM's. I pulled the vaccume line off the EGR and that fixed it,it runs just fine.Like its supposed to. I plug the vaccume line back on the EGR and it runs rough off idle again. So I replaced the EGR valve and cleaned out theminimal carbon I saw onmanifold with brake cleaner, took it for a drive... same thing... WTF? Ok I go back to the store and I get a EGR Vaccume Solenoid, thats got to be it, replace that, drive the truck... same thing... c'monnn... now its late, I pull the IAC valve, it looks fine, I clean it out punch a new gasket and reinstall, same damn thing. Why is it getting too much air off of idle? I would assume Throttle Position Sensor or IAC? Hell, matbe even aMAP.I dont want to keep guessing and emptying my wallet. Last year the fuel pump went so I replaced the pump, sender, straner and filter, at the beginning of the summer I put new plugs, cap roter, Ignition module, wires, PCV, O2and air filter, I would replace the coil but what would that have to do with the truck runing smooth when I remove the vaccume line? I googled the symptons and it seems common but no one has the answer http://www.chevytalk.org/fusionbb/sh...78/tid/195543/any ideas?

 

when you pull the vac line are you plugging it or leaving it open?...

 

leaving it open, but its the same result if i pull the wire off as well