I ordered a new set of the complete rubber hoses that comprise the pcv system on the car. Such hoses are the air box hose, the idle air valve hoses-upper and lower.,and a breather hose that goes to the front of the motor somewhere near the pwr steering pump. My question is this: I replaced the lower rubber hose that attaches to the idle air valve at the bottom and it connects the fuel pressure regulator and ends up down below the fuel dist plenum. After I replaced thhis one hose, the car wont idle when it is at operating temp. It idles fine when it is cold. I literally have to hold the gas pedal to idle the car or will stall. The fuel mixture is adjusted to the proper setting and the fuel filter is new. I cannot believe that one rubber hose can cause the car to stall when hot. Any assistance will be appreciated. Thanks, Joe

I have seen a couple of things like this...The hose can have a restriction in it, even a new hose. Also, the idle valve could be malfunctioning.

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Benzmac:
Donnie Drummonds
1991 GMC Syclone
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Thanks Benzmac: I found the problem: A bad plug wire.