Hard start on a '95 Pontiac Grand Am

Friend of the family was asking for help on this.

Recently replaced parts include ECU, plugs/wires.

On cold starts, the motor will need cranked, pause, crank, 3 or 4 times, before it starts. Sometimes backfires during this. Once started, starts every time.

I guess they had a mechanic take a look at it, mechanic put a gauge on the fuel rail, didn’t lose pressure rapidly, so it doesn’t sound as if it’d be the fuel pressure regulator or even a leaky injector for that matter. Don’t think it’s the pump, since it’s only on cold starts. Runs like a top otherwise.

Something that they had mentioned as well, is that around 55mph (not sure on RPM, no tach) the car studders. Sitting in park, if you run the rev’s up, it does it as well and sounds like a rev limiter, but there’s no tach and it sounds like an awfully low RPM to be a rev limit. Obviously if it was a rev limiter it shouldn’t do it on the highway, anyways.

Any ideas?

crank sensor
the 3.1 are notorious for that
i was gonna mention Fuel pressure reg but you already ruled that out

x1

lower rev limiter in park or nuetral then if your in gear so that explains the low RPM shut off. but i would guess crank sensor or fuel pump. bleeds off over night and then takes a while to build pressure up and thats why on cold starts it takes a while but on warm starts it fires right up because it hasnt bled down yet