My 1992 4.0 Explorer has a high-speed engine
miss: it starts and runs fine in the morning but after driving at highway speeds for several hours, it begins to miss. As you continue to drive, the miss increases until it won't run and won't start. The next morning, after "resting" overnight, it starts and runs completely normally and gives no problems while driving around on short trips. It seems like higher speed, higher outdoor heat, and going uphill all make the problem worse, maybe higher altitude worsens the problem too.
For me—no expert—it feels lil a fuel deliverability problem: 1. slowing the car seems to lessen the miss; 2. if you "floor it" while it's in miss mode but not missing too badly, there's an immediate hesitation miss before things smooth again, feels like the accelerator pump isn't doing it's job; 3. when you try to re-start it after it dies on the road, it has that "ran out of gas" feel: while the starter
is spinning the engine, there are a few little "ka-pocketa-pocketa" hits like a small amount of gas is getting through and it's trying to fire up but is starved.
Lastly, the car seems to be using more gas than usual while running normally.
Thanks, ***** *****