'94 F150 with 302 and 4 speed auto. When I first got it I assumed it had a shift kit since the shifts especially 1 - 2 were really snappy and it seems to have a mild stall converter. The guy I got it from got it from a young guy in the Navy who I'm told had changed the engine and trans, It also has glass packs - seems it's been mildly hot-rodded. After changing the pan fluid (not a complete flush) the really snappy 1-2 shift went away. It shifted okay but it was spongier. However, over the course of about 25 - 30 miles of driving it got crisper again, it's basically back to what it was. This apparently was the first time the trans fluid had been changed - the plastic shipping plug was still in the pan, there was some fuzz on the magnet. The fluid wasn't brown but it was darker than new.

I don't have much experience with shift kits, is this how they behave after a fluid change?

 

It had to have a fluid change with a shift kit and a new torque converter.
Maybe just some air in the system.

How many miles?

 

No idea how many miles on the trans. The guy I got it from didn't have it that long, he bought it from the Navy kid - per his explanation. Wondering if it was some kind of "crate trans" that came with a kit and converter and was sent with a shipping plug in it? Would anyone other than the Ford factory put a shipping plug in the dipstick tube? I'd never heard about the shipping plug until seeing a video the other day that mentioned it and when I pulled this pan it was there. Supposedly this engine and trans came out of a Mustang - could a Mustang come from Ford with a shift kit and stall converter? The odometer on the truck shows 293,000 miles, there's no way that fluid had been in the trans for that long and the trans exterior seems too clean to have that many years and miles on it.