17th Jul 2014, 21:45
I just purchased an '85 two months ago... with 79K miles. Love the car. I was experiencing some stalling... and sudden jerking movements at highway speed. Drove me crazy... I thought it might be tranny-related, but my mechanic said that was fine. I did four things, and I'm not sure which helped, but I have no further issue and it runs like a top now:
1. Replaced the fuel filter.
2. Ran a couple containers of injector cleaner through.
3. Squirted some WD-40 on all the throttle linkages.
4. REALLY tightened down the wing-nut on the filter housing.
I actually think #4 did it. If there are any kind of air leaks, it will cause sputtering, coughing, and stalling here and there.
Hope this helps!
3rd Jun 2014, 21:25
I have an 85 Grand Marquis with the 302 V8. You might want to have your throttle position sensor checked. It is located on the left side of the throttle body as you face the engine. Check to ensure that the wiring is in good shape and not cracked, heat damaged, or broken. A bad TPS can cause serious problems such as stalling, hesitation, and sluggish performance.
Check the air temperature sensor (located on the rear base plate of the throttle assembly). Ensure the plug is clean and firmly seated.
Have a mechanic check your fuel pressure. These vehicles run off electric fuel pumps. Standard pressure needs to be between 34 to 36 PSI. Anything lower can cause poor performance and stalling.