Mechanics

MY RPM'S RACE UP TO 6000 WHEN I START MY ENGINE AND THEN IT WILL USUALLY DIE

1989 GMC Sierra • 235,000 miles

99 GMC Sierra 5.3 235000 miles. When I start it up the RPMs jump up to 5000 to 6000 and back down to under a 1000 and will usually die. If it does not die it is a real low rough idle. When I try to drive the vehicle it will gradually accelerate until I reach about 45 mphs. Without pressing accelerator and start surging. When I come to a stop it surges. I have replaced Intake manifold gasket, Mass air flow sensor, fuel regulator, throttle position sensor and pcv valve.
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Jimmy.46
May 5, 2012.




Clean the idle air control valve and EGR valve and see what happens

Tiny
Rasmataz
May 5, 2012.


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