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Engine misfire during acceleration and loss of speed

I have a 1997 mercury grand marquis which up until 4 days ago was running perfect I had already been driving for about 3 hours and was on my way to work on an interstate and started losing speed pressed on gas harder and engine misfired and speed kept dropping I pulled over let car sit for a minute and was manually pulling throttle under the hood and it kept having a slight misfire when I pulled throttle got back in car let sit for a minute and got back on the road car did fine for another 5 miles then did same thing made it to work then when got off work no problems out of car at all which is only an hour drive and didn’t drive car again until today had been driving another 3 hours probably I had a lot of stuff to get done before work but on my way to work again on a different rd though I had same problem I was passing somebody this time and low fuel light came on but had a full tank of gas but didn’t have to pull over this time I just let off of the gas and let the car coast and it was back running fine and fuel light went back off I have no idea what it could possibly be because it only does it after long periods of being driven if somebody could give me some answers I would appreciate it

Does that car have an external fuel filter? If so, replacing it is worth a shot.

Driving a car with a misfire can turn a minor problem into a major one.

That said, has any engine warning light come on? This vehicle has OBD2 (onboard diagnostics) and it’s possible the vehicle has stored DTCs (diagnostic trouble codes) that would help with where to begin searching for a problem/solution.

Yes it does but a brand new fuel filter was put on it 3 months ago

No it hasn’t not a single engine light has ever come on on that car

Difficult to say without a code. I’d go ahead and change the plugs and wires if they are almost due changing. If that doesn’t help, I could make guesses, but several guesses could cost more than a shop diagnosing and repairing it, unfortunately.

Not familiar with your ignition, but if possible, try to see if you have a strong blue spark

Double check that the gas tank is full. Your symptoms remind me of when I’m about to run out of gas on my Corolla. Especially if it seemed to get worse during accelerations, b/c that can force the fuel away from the pump s fuel pickup. It’s possible somebody siphoned your gas tank overnight or something. Bad gas should be considered too. Another idea, something wrong w/the evap system so the gas station pump shuts off way before the tank is filled. Final idea, the car s fuel pump in on the fritz. A fuel pressure test would show that.

I would agree with the low gas but I had just put $50 worth about a hour before that and had been driving since then

Pointing more and more to a fuel pump problem.