Highway surging idle

2002 FORD MUSTANG
130,000 MILES • 4.6L • V8 • 2WD • MANUAL
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JONEST28
  • MEMBER
  • 12 POSTS
Good morning! The issue I'm having is with my car listed above GT. I have an intermittent problem that comes and goes. When I drive and rev it to about 3,000 to 3,500 or even past 2,500 when I push in the clutch it's wanting to hang around 2,000 rpm's. It doesn't always do it though. If it's stuck at 2,000 I can go back into gear and idle it down but as soon as the clutch is disengaged it goes back to where it was.same thing with revving it up it drops right back. It will also sometimes hang and then drop to 1,500 and rev to 2,500 and cycle. This only happens when I'm moving. I can let it hang or surge for as long as I can with no change. The only solution I've found is to quickly shut the key off and back on. The engine starts back on its own and the issue will either go away for the rest of the drive or until I pass 2,000 again. Key thing if I come to a complete stop with it doing either the hang or the surge it will drop in rpm and die. It has zero issues at idle and no check engine light. I have noticed it seems to happen more on my drive home from work in the afternoon vs morning commute. Approximately 65 to 70° and 90-100.
Jul 18, 2019 at 7:32 AM
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SCGRANTURISMO
  • CERTIFIED EXPERT
  • 4,897 POSTS
Hello,

There are a couple of things that could be wrong here. There could be an issue with your vehicle's PCV system or an intake leak. In the diagrams down below I have included the factory diagnostic troubleshooting guide pinpoint test for your vehicle's PCV system. Please go through this guide and get back to us with what you are able to find out. If needed, we can send you the intake leak pinpoint test next.

Thanks,
Alex
2CarPros
Jul 19, 2019 at 1:27 AM