1994 f-150 Funny shifting issue

I got a funny shiting issues that happens infrequently that I can no figure out. It happens after driving the car for a while on the highway, but not everytime, and not just on the highway.

Here is my problem… when cruising down the highway the check engine light will come on stay on for a around a minute, the the check engine light will turn off, then of which my truck will lose power, not accelerate no matter how much I stomp on the gas, until my speed drops to under 55mph. Once I get down to 55mph the truck will drop 2 gears into 3rd gear and then I can accelerate back up to speed. This will repeat every few miles. The computer will not store the check engine code, so no codes are pulled.

There are code readers that will pull the codes. They should be in there as history codes. Unfortunately most generic code readers (e.g. at auto parts stores or one you may own) won’t be able to do it. So you’ll probably have to pay someone a basic diagnostic fee to have them scan it with a professional grade scanner.

Is there anything else you notice during these “episodes”? E.g. maybe a twitchy speedometer or something?

Now that you meantion it, the speedometer sometimes does twitch, I have not seen it happen at the time of this sitaution but there are times when the speedo bouces 2~3mph.

I can’t think of anything else that it does. It used to only happen on colder wet days but has been happening in different weather conditions now.

I asked about a twitchy speedometer because one thing that would create what you describe is a problem with the vehicle speed sensor. The computer(s) needs the speed signal for transmission control. If the computer can’t tell what the vehicle’s speed is it won’t know what to do with transmission control. I’m not a trans expert so I’ve got no specific info about for you. But if the PCM loses speed signal it will probably neutral out the transmission and perhaps other things - a “Safe mode” which is often called a limp mode for a transmission. If the disruption is momentary I could see the computer allowing things to return to normal.

I’m just guessing - of course. That’s no basis to do anything, so I’d have it scanned, but wouldn’t be surprised if you came up with a code for some issue with speed circuit/signal.

When you lose power and you stomp on the gas, will the engine rpm’s increase while the vehicle is slowing down?? Is the engine racing while the vehicle steadily loses speed?? If the engine speed increases then you’re 4th gear frictions are gone. The transmission will have to be rebuilt.


The engine does not race. It stays in 5th and chugs.

Oh and another thing it does when the episodes happens is, if I get off the highway it will try starting off in 3rd instead of starting off in 1st gear.

A few other things. If I speed 75+ the issue seems to not happen until i slow down to a non speeding MPH. also I have a smell of gas when I get out of my truck.

Get the computer scanned, we need those codes before we can go any further.