Let me start by saying I'm new to the site and Hello All.
I have a 97 F150 5.4L that, all of a sudden, developed a very hard downshift. As long as I'm driving and accelerating it upshifts with no problem. But when I take my foot off of the gas and slow down the tranny drops very hard as it downshifts. At one point I had it drop from 3rd to 1st, the tires chirped and truck did a serious nose dive. It has only done this 3 times but now I'm afraid to drive it. Am I looking at a new tranny or could this be electrical?

 

Have you checked the tranny fluid?

 

Yes. It's full and clean. When I bought the truck the seller had it flushed by our local dealer. Now I'm wondering if it was to hide something. I have 124,000 and this just started.

 

When was it flushed? Within the last month or so? I remember reading on here at some point that its not good to flush and engine or trans thats over 100k miles because it can actually cause damage.

D

 

It was done right around 100,000 miles. I'd have to look at the receipt for exact but not much further than the 100,000 mark. Now that makes me nervous if it wasn't supposed to be done.

 

Im not a tranny guy so I cant be certain if that is the problem I just remember reading about it. Hopefully someone else chimes in and help out. Sorry to be the bearer of bad news if that is the problem. I'd say from here the best thing to do would be to find a good/trustworthy driveline mechanic and have them diagnose it and then go from there. Good Luck.

D