98 Accord V6 revs up and down

I have a '98 Honda Accord that revs up and down when started and idle. It sounds like someone is stepping on and off the gas pedal. The cyclic “revving” doesn’t stop. I have not used the car on a regular basis since last fall. I replaced the EGR valve and put in a new air filter. The check engine light has been on for a while, but the codes all point to the EGR valve and vacuum flow issues.

Does anyone have any ideas as to what I should be looking at? O2 sensor? Fuel filter?

When an engine surges up and down like that, it usually points to a vacuum leak somewhere on the engine. Since there’s a code for an EGR vacuum flow issue, this could be what’s causing the engine surging.


I replaced the EGR valve, but the problem remains. The old EGR valve didn’t look too bad, either.

It’s not the EGR valve, it’s the vacuum leak that’s causing the surging idle. Find the leak. It may be in the hose leading to the EGR valve. That’s what Tester is trying to tell you.

All too often people will blindly replace a part while ignoring the hoses/plumbing/connector leading to/from the part.