My engine (carb, AT) starts rapidly cutting out and in after 20 mins of driving. I lurch down the road with steady throttle but tach oscillating regularly between approx. 2000 and 2500, on a 1 second cycle.
This will go on for several seconds, then it might run perfectly smooth for 100 yards, then resume. Putting it in neutral makes no difference. Eventually it starts to stumble and I have to pull over. I don't have to be cruising; first appearance was when it died at a red light.
But if I shut off the engine, wait a couple minutes and restart, it goes away. I've already replaced the igniter/coil and ignition wires. The cap and rotor are recent, and I swapped the ECU. No dice.
I'm thinking radio condenser next. It's unlikely, I know, but it's the last ignition component unchanged. If that's not it, I'll have to start looking at vacuum leaks. It doesn't seem like a fuel supply problem.
Any other suggestions?
TIA, Joe