Hi, guys. I have a manual 2007 Forester X with 166k miles. I'm having an intermittent revving issue. For example, normally if I'm in 3rd gear, at say 3.25 RPM, I'll shift to 4th and the RPM goes down to 2. But now sometimes if I'm in 3rd gear at 3.25 RPM and shift to 4th, it goes down for a split second but then it's over 3, maybe up to 4 RPM. It doesn't only happen in 4th, it happens in 3rd, 4th, and 5th. It's not just when I shift, either. Sometimes I'm just cruising in 5th at 2.5 RPM, then suddenly it shoots up to 3.5 then back down. Is it the throttle body or IAC?

 

Also, I got a P0460 error code. My friend who diagnosed the code thinks I just need a new gas cap. Is that a common culprit? Could the 2 issues be related?

 

Thanks in advance.

Edited September 14, 201510 yr by SpockThe Jock

Sounds like your clutch may be slipping.

Try giving it gas, but apply the brake gently at the same time, to stop the road-speed from increasing.

If the engine RPM goes up, then the clutch is slipping, and needs replacing.

Thanks, forester2002s. I will try that right after work today and let you know.

It does indeed appear to be the clutch. Thank you.