Overheated, now stumbling/stalling above 3K RPM

[GT_M3]

Car had been sitting for a while. Battery was dead, so I jumped it and let it idle. Came back outside about 15–20 minutes later to find it steaming and clearly overheated, coolant everywhere.

I did a full cooling system refresh last year, minus the expansion tank — which I found split in two. That's been replaced now. Could the thermostat have stuck closed? I haven't pulled it to inspect yet.

The engine starts ok, but won't pull cleanly past 2,500–3,000 RPM. No codes on scan. No white smoke from the exhaust. Oil looks clean — no milky residue on the cap or dipstick.

What should I be looking at for overheat damage? Spark plugs? Coils? VANOS? Compression test?

[sapote]

What should I be looking at for overheat damage? Spark plugs? Coils? VANOS? Compression test?

Fill up coolant to proper level, drive it normally until reaching operating temp ~ 85C, shut off let cool overnight. Next early cool morning, remove each plug look carefully for condensation at the tip which indicates cracked head.

[JakeM346]

Odd. The shake between 2500-3000 rpm is something I have to in standstill. I believe probably most have it but don’t notice because why would you normally rev the engine in standstill. I’d figure it’s probably due to some clutch/ flywheel harmonics

[01SG]

That's what my e36 did when the head gasket went.

[ChapterM3]

Oh man, reading your post made me immediately think head gasket. Leak down test would tell you immediately if cylinders are sharing compression from a broken head gasket - that’s how I ultimately found out mine was gone between Cyl 5 and 6