Engine revs up to 2,500-3,000 RPMs?

1986 FORD MUSTANG
94,000 MILES • 5.0L • V8 • 2WD • MANUAL
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ROB1986
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  • 1 POST
Changed the idle air control valve with a new one, still on start up the car will rev up out of nowhere to like 2,500-3,000 and it revs up while even driving it sometimes, on startup if it does it I will turn the car off and restart it and everything's fine?
Jun 14, 2023 at 10:49 AM
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STRAILER
  • ✓Experienced Mechanic
  • 55,249 POSTS
It sounds like the PCM is bad or you have a bad ground somewhere. We should run the codes though to see what comes up. Here is a guide that will help, and I have included how to change the PCM out in case you need it:

https://www.2carpros.com/articles/ford-lincoln-mercury-obd1-1995-and-earlier-diagnostic-trouble-code-definition-and-retrieval

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Jun 16, 2023 at 12:23 AM
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