"Bucking Bronco" is the only way i can describe whats wrong with my 1988 n/a Automatic FC...

Every time I'm out cruising around town she runs fine and its all good, but it seems as soon as she warms up she starts to "buck". The problem only happens when I'm trying to keep the car at a steady speed, acceleration isn't affected by it. When I'm going down the highway and I'm holding the needle steady at 60 or 40 the car decelerates and accelerates, decelerates, and accelerates, almost as if it were a manual and i were pumping the clutch in and out. When i first had the problem it was way more severe, I'm talking jerking up and down crazy, i turned the Overdrive off just so it would stop. After that i changed the transmission filter and Transmission Modulator and the problem actually went away for a while, but slowly came back. I tried flushing out the Transmission, but that didn't work either. I can only think that the problem is tied to the Auto Transmission somehow (And i wish i had the money to swap the bitch out). A Friend of mine has told me it sounded like a vacuum problem, but where do you look for a vacuum leak?

I've searched around and i think i found maybe one guy who had kind of the same problem as me, but no solution was given. I've also posted about this problem the first time it happened and i came back to read reply's, only to find everyone arguing about how a automatic transmission works and if i checked the fluid level...

If anyone can give me an Educated guess on what could be the problem or what i could look for I'd humbly appreciate it.

 

I know absolutely nothing about the auto tranny RXs, but when my car had an out of adjustment TPS, it would buck at part throttle when cruising or getting on the gas after deceleration. There is a lot of information about checking the TPS. If you have a multimeter and know how to use it, this is a 5 minute job. Hope that's your problem!

 

Throttle position sensor.