I cleaned the air valve, the throttle body, the EGR valve body which had a little carbon build up, installed new gaskets; but engine still won't idle smooth. I checked the vacuum sensors and the vacuum switches, they all check out OK. I checked all the vacuum hoses for leaks and all were good. Engine still revs up and down all on it's own. 800rpm to 2700rpm then back to 800rpm. When I disconnect the vacuum switch for the fuel rail pressure reg the dash pot for the throttle positioner will start to pulse the throttle up and down. When I disconnect the MAP sensor the engine will idle rough and then die. It also will register a trouble code for the MAP sensor; but will clear out when I reset the ECU. So I think the MAP sensor is good. I actually replaced it a few days ago. I'm really stumped on this one. Can someone please help. Thank you.
Tuesday, May 22nd, 2007 AT 11:45 PM