Weird miss only afer fully warmed up

[Splinter]

Unfortunately it's on a car me and my GF are looking to buy so I can't really dig into it.
93 Turbo Wagon.
Cold and Normal temp it runs fine, pulls strong, sounds good. No problems. About 10 minutes after it gets up to normal temp it starts missing a beat every 3-4 seconds, both at idle and above idle. Car is almost undriveable under load when it gets like that. No acceleration. But it's totally fine before it starts happening.

Knock sensor, Idle switch and Purge solenoid codes. None of which really stand out to me as causing something like this.

Anyone come across this before? I want to try and figure out if we can fix it before we buy it, because she's going away to school over the winter and I won't be able to help her with it much once she's gone.

[ericem]

My car did it and it ran fine just annoying sometimes. I think it is voltage related, or possibly IAC related.

[Legacy777]

I'd check the coil, wires, and plugs.