Acceleration intermittent problem 90 Grand Marquis Calif car

[I Like FE]

I have an intermittent problem.
1)The other day i came to a grade and put my foot further on the accelerator and it started loosing speed, I backed off the pedal and in slowly gain some speed (driving time 25 minutes).
2) I was going to work on the on-ramp accelerated and it lost power, let up and it slowly accelerated (driving time 10-12 minutes.
3) Last night took it out on a rural road. Doing 55 stomped the pedal and it lost power, letup and it slowly accelerated. Turned around headed back south. Stomped the pedal went thru all gears 1-2 shift slammed hard others firm. Slowed to 45-50 stomped downshifted and worked same 2X. Turned around headed back North slowed and stomped 3x all ok. Turned around again headed south tried again 3x all okay (Driving time20 minutes).
4) this morning I was following a Tractor Trailer an I felt it was going to slow for the slow lane of the freeway. I moved to the left an punched it. I realized it did downshift from OD. I did not rev up and I lost speed and distance to the Tractor Trailer. I let up I shift back into OD and slowly accelerated and I pull back in behind the Tractor Trailer (driving time about 25 minutes).
5) After work I started out on the freeway shifted up okay on hard acceleration. Exited driving surface streets ran errands city driving continued because freeway slow opposite direction because of "Hotlanes". Finally got after other errands on the freeway going home merging on was okay. Got to a grade and once it had to downshift to maintain speed it lost power. Letup back it OD slowly accelerated (driving time about 20 minutes).

No check engine light.
Not sure what to do. I guess check fuel pressure. Check to see if OBD-1 has any codes.

Any help appreciated.

[gadget73]

Sounds reasonable. Change the fuel filter if you haven't. Is this a model with a mass air sensor? If so, clean it and make sure that the air intake tube isn't cracked or loose. Check for any vacuum leaks as well.

[jaywish]

So many choices.
Original Cats?

[knucklehead0202]

If it's a '90 CA car it'll have a maf. I'd clean that, change the fuel filter, and probably check for codes just for kicks. Because it's an intermittent problem it probably wouldn't do you much good to check plugs but maybe you've got a cooked plug wire making occasional contact with something. Possibilities are endless but start with the simple stuff. Does it seem like the transmission isn't responding as it should when these events occur? Or does it seem more like the engine just isn't getting with the program?

[Tiggie]

Original Cats?

My first thought also.

[gadget73]

Cats only go bad if there is something else wrong to begin with. The originals on my Mark VII were perfectly fine well over 200k miles, but the shell was cracked on one and I didn't think it worth the effort to attempt to patch them. They may be bad, but I'd want to know why so the next set don't fail.

[Chuck Norris]

My Caddilac had the exact same symptoms with a bad MAP sensor, but it set a code.

[ralph.robichaud]

I have an intermittent problem.
1)The other day i came to a grade and put my foot further on the accelerator and it started loosing speed, I backed off the pedal and in slowly gain some speed (driving time 25 minutes).
2) I was going to work on the on-ramp accelerated and it lost power, let up and it slowly accelerated (driving time 10-12 minutes.
3) Last night took it out on a rural road. Doing 55 stomped the pedal and it lost power, letup and it slowly accelerated. Turned around headed back south. Stomped the pedal went thru all gears 1-2 shift slammed hard others firm. Slowed to 45-50 stomped downshifted and worked same 2X. Turned around headed back North slowed and stomped 3x all ok. Turned around again headed south tried again 3x all okay (Driving time20 minutes).
4) this morning I was following a Tractor Trailer an I felt it was going to slow for the slow lane of the freeway. I moved to the left an punched it. I realized it did downshift from OD. I did not rev up and I lost speed and distance to the Tractor Trailer. I let up I shift back into OD and slowly accelerated and I pull back in behind the Tractor Trailer (driving time about 25 minutes).
5) After work I started out on the freeway shifted up okay on hard acceleration. Exited driving surface streets ran errands city driving continued because freeway slow opposite direction because of "Hotlanes". Finally got after other errands on the freeway going home merging on was okay. Got to a grade and once it had to downshift to maintain speed it lost power. Letup back it OD slowly accelerated (driving time about 20 minutes).

No check engine light.
Not sure what to do. I guess check fuel pressure. Check to see if OBD-1 has any codes.

Any help appreciated.

I have an 88 MGM that occasionally does that, as soon as I feel it's beginning to lose power, I downshift manually from OD to 3rd gear D and instantly get back in the power band.

Ralph


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