1982 240 Turbo Wagon m46

I need to crank it about 4 times before it'll light when it's cold. And then I need to give it gas until the temp needle goes into the normal range or it'll stall on me. Idle tends to vary somewhat.

After it warms up, it'll idle pretty much fine. Driveability seems okay too.

The problem starts after I've driven it about 10 miles or so. Now the car tends to have a poor idle at stoplights and will backfire when I take my foot off the gas and leave the car in gear.

This gets worse the longer I drive the car.

Eventually, the car will begin to stumble in the higher gears (4th or overdrive) when you drive to give it gas. This is especially noticeable while cruising on the highway.

The longer I drive it, and the hotter it gets, the worse the symptoms.

If I turn the car off after it's hot, it'll start up immediately, as opposed to when it's cold, which takes at least 4 cranks and a heavy foot to keep the revs up to prevent it from stalling until it warms up.

I've had the warm-up regulator and the idle control valve replaced which helped control the surging idle somewhat but nothing else.

I'm open to any and all suggestions because I'm at a loss.