i have a 1995 gmc jimmy when i go to brake the RPMS shoot way up and its hard to stop the truck whats the problem
Check your brake booster vacuum lines for leaks. You may need to replace your booster. Another guy had the same issue as you, he would hit the brakes and his idle would shoot up. In his case it was a plugged IAC valve. But his was a Toyota 4X4.
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