1984 Porsche 944 surging on idle

[Teeckz]

My 1984 Porsche 944 engine started surging on idle after warming up, chewing up gas. Replaced the catalytic converter and worked better for a couple of days until the weather got hot. Wouldn't idle smoothly even when first started. No problem starting, but engine races uncontrollably at idle. What else am I looking for as a cause?

[jjeffries]

I’d start by looking for vacuum leaks in all the hoses managing air flow into the engine.

Best of luck, John

[onZedge]

In addition to the hoses, check the intake manifold gaskets. Exact thing happened to me twice and it was the IM gaskets both times.