90 bronco,HELP!!!!!

[sattalitemike]

First, I must say this is the coolest Bronco site that Ive come across. Im having a little trouble maybe somone can help me with.I have a 90 bronco 5.8 with a new rebuilt motor dyno tested from factory.all my sensors are new within 3 months,has headers custom exaust/with spintech muffler and k&n fipk.it passed the calif.smog test with flying colors ran aprox 150% cleaner than required by law.about a month ago my checkengine light lights up,*** over,I break out my trusty ford comp decoder it spits me out a code saying voltage to egr solenoid is to low for self test(in the key on engine off setting) so I check my harness and wires going to solenoid they all look good? so I bought a new egr position solenoid/sensor installed it disconnected neg cable from battery for five min.I realize after clearing codes it can run rough for a little while but what ended up is the check light went out for 10 mins. or so and then stalling, backfiring,and just running real bad checked new codes still gave me the same code and added a code which was the oppisite of the first (voltage to egr positioning sensor to high for self test) so now i have a non driveable bronco so for now i have put the old egr positioning sensor back on and the engine runs great with the check light back on any ideas? anyone? any help would be awesome thanx sattalitemike thanx everyone who read my ad cant believe it ended up being a bad egr valve itself replaced it and no check engine light anymore