QUESTION: I have a 1990 Ford F 250 with a 4.9 inline 6 the truck idles great but after the truck reaches running temperature it starts to bog down under high RPMs what could cause this problem
ANSWER: Hello, has any recent work been done ? Ie... Maintenance ? Does the service engine light come on ? Are you driving it when it does this or just idling and you are raising the isle manually ?
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QUESTION: The head on the engine was replaced.the service light is not on. It only does it when driving. When parked it runs fine during high or low idle
So at a steady cruise high speeds or any speed, it surges or starts losing power ? Are you familiar with the engine components ? Try disconnecting the EGR valve by taking the vacuum line off it and reroad test . If that doesn't take care of it, locate the fuel rail and disconnect the vacuum line from the fuel pressure regulator and reroad test and get back to me please