Ford windstar/freestar jerking motion at 35mph

Have 2002 windstar and 2004 freestar. When cruising between 20 and 45 mph i feel a jerking motion like the engine is missfiring. 5 months ago had the 04 freestar engine work, one cylindar missfiring and then noticed this after repair. Both vehicle @ 115000 miles

Is this the same one that was repaired 5 months ago? And you noticed this immediately after the repair but didn’t go back?

There are countless possible causes for this symptom. Unfortunately, since it’s been 5 months since your last repair you may have to pay again, but the vehicle needs to be looked at. It could be ignition related, fuel delivery related, tranny related, or even a bad engine mount.

Actually, it was in for ignition issues(spark knock) and the jerking never occurred before the repair. So i discard tranny or engine mount, i suspect fuel issue. Repair center replaced the GAS CAP saying it leaked causing engine light to go on.
Unfortunately, repair was performed when this was a company car and i didnt have time to return it, when i planned to then company had a downsizing (go figure) and so i was able to buy car, @ good price. I would have taken back asap but took weeks to get title etc. so i will have to probably pay.

If they changed spark plugs on the Windstar which has the jerking now, the spark plug wire may have slipped off the spark plug. Or, the problem could be unrelated to the prior problem.
Please refer only to the Windstar which had a problem and which, now, has a problem. I’m still working on my first cup of joe------I confuse easily until I get to cup #3.
We need any codes if the check engine light is on, or flashing. Several of the chain auto parts stores will do the scan, for free.

funny though, just for more diagosing, when i use the cruise i do not feel the same sensation of jerking, no misfire etc. This is what is baffeling

i am having this exact problem. when car gets to about 40 mph, it hestitate and sounds like a pop in the engine compartment. after that hesitation, i stopped and then started again and the engine started popping and the check engine light began flashing. i stopped by an autozone and it says P0301, cylinder 1 misfire. i started the car again and drove off and it ran ok for about 10 miles and it started again at around 40 mph. one thing i tried was to put the gear shifter into 3. now when i drive it doesn’t seem to have the problem. also, the engine runs fine when idling, no popping, no flashing engine light. why does it happen at 40 mph?