Sudden Rough Idle/95 Jimmy??!!??

I have a 95 Jimmy 4x4 sls 2dr.4.3 vortec, 175,000miles. I've had it over a year now and it's been a really good truck. But it started running rough while in idle speed, seems to clear out some while driving but not completely. The check engine light came on and I took it to Advance and had the OBDII scan done, and it brought up P1506, manufacturer control,auxillary emissions. I've changed the Spark Plugs, Wires,IAC, Cleaned the EGR valve and installed new screen gasket, after cleaning the EGR valve it seemed better until I gave it a little gas, then it started rough idle again????? We can unplug the TPS and RPM'S increase, but then goes right back to low RPM within a Minute or so. It just seems like maybe something is choking it out. I don't want to have to keep throwing parts at this as they are not cheap!!! Can anyone help me PLEASE!!!!????

I have a 95 Jimmy 4x4 sls 2dr.4.3 vortec, 175,000miles. I've had it over a year now and it's been a really good truck. But it started running rough while in idle speed, seems to clear out some while driving but not completely. The check engine light came on and I took it to Advance and had the OBDII scan done, and it brought up P1506, manufacturer control,auxillary emissions. I've changed the Spark Plugs, Wires,IAC, Cleaned the EGR valve and installed new screen gasket, after cleaning the EGR valve it seemed better until I gave it a little gas, then it started rough idle again????? We can unplug the TPS and RPM'S increase, but then goes right back to low RPM within a Minute or so. It just seems like maybe something is choking it out. I don't want to have to keep throwing parts at this as they are not cheap!!! Can anyone help me PLEASE!!!!????
Problem fixed except for some weird whistle noise between the engine and firewall. This forum really helps out alot!!! Now I guess I'm going to try to find something on this whistle noise?? Thank you I appreciate the help.

Mine is doing the same thing. What was the fix for this, I don't see any replies???

I ran into the same problem. What you need to do is take the top of the plentum off whitch is the cover for the fuel injecotrs.Then have someone turn the ignition to the on position without starting the truck. meanwhile you will be looking for fuel leaks usually the supply hoses to the cpi unit will be leaking good luck.

this thread is almost 2 years old, please refrain from posting in old threads.