Idle problem.Thought fuel, but it was bad ECU

Thank you too.
I checked back because I wanted to add one thing about the symptoms.
The way the car was acting really threw me.
It ran fine otherwise.
But when I would come off the interstate or maybe down a long road I had to be ready to keep my foot on the gas when it stopped and got to idle speed.
I would "feather" the peddle for a moment till it would run.
For lack of anyting else, I kept thinking "dash pot".

That and the other weird thing I said about it would be sitting there idling and the thing would act like something was making it slow down speed up.
This had been going on for a while. But what got me going on it was the thing just died one day. But it restarted and I got home.

It really is purring now though. When I put the drivetrain in from the cop car, I put a new oil pump, timing chain and valve seals in the engine. So it may outlast me.
If I knew someone local I could pull the engine and give it to for a rebuild I could trust, that's the way I would go someday.
I don't have the time or equipment to do that. (or experiance) I'd farm it out.
Not something I want to be in a learning curve on.