Full Throttle/car Falls On Its Face


New Member
Feb 1, 2014
Hello all, my issue is with my 1988 mass air 306 powered mustang. It is a 5 speed, 4.30 geared car, my problem is that when i just run thru the gears without matting the throttle the car runs fine....but when i matt the throttle the car acts like it dying until i let off the throttle. I have a fuel pressure gauge that i can see, and the fuel does not drop with the acceleration.....so i am curious whether the tps could be an issue or something else......any ideas out there for me to try? Thanks
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Thanks Mad, out of town working right now, will check when i get home...had this happen once before and changed the tps, and it cleared up.....this time we just changed mass air meters and wala....back again. Changed tps again but to not avail, and the last codes pulled did not point to an issue with the tps or pip.
The ign. module is the most likely culprit. I've had 4 of them fail on me in the most unusual ways... One simply didn't advance the timing at all; so it would run okay squeezing the throttle & fall on it's face if I went to WOT..... Sound familiar? ;)
Tony, that decribes my problem to a "T"........thanks for your input on this....but let me throw one more thing to this mix. We were at the track and decided to change mass air meters......that is all we changed/touched.......and that is when it decided to go awol.......I believe you guys are on to something. thanks again. I will test it when i get home and hopefully just have the change the TFI?
On this car for sure i need to again....it is/was a sd conversion.....crazy part is that it happened once before and i changed the tps and it went back to running normal.......down the road, months later i changed the mass air and boom, its acting up again....called myself checking the mass air plug as they have been known to act up, but all of the pins are straight and connector is tight....btw thanks for the input.....electrical stuff drives me nuts.
Mine is still doing exactly what OP described, somewhat inconsistent. Ran good last night. Tonight falls on its face at fullthrottle. I'd shut if off and try again. Worked a couple times.

Ima check/clean the MAF tomorrow. Will start there i guess.
Mine did this a couple years back. I chased fuel and TPS and it seemed to solve it, but then come back a few drives later. I change spark plugs, and spark plug wires and cleaned all sorts of connections and sensors.

Ultimately it ended up being the ignition coil. I had a 20 year old Accell coil on there. I swapped it to a good, used OEM coil on a hunch and the problem went away and never came back.

Symptoms were that when I went WOT, when I got to 3000-3500RPM, it's like the car would hit a wall and fall on it's face and not accelerate anymore. I had no codes, no misfire.
I had the same problem in my '95. Started out as an intermittent blip while cruising and got worse and worse until the car would ultimately stall any time you'd try to give it gas.

My issue also ended up being with a ten-year-old MSD coil. Threw a new Motorcraft unit in and it's been perfect ever since.