Torque converter lockup question

[pstroke tonka]

First off, I'd like to say I'm new to the site and I am liking everything i read so far! Second is the issue i may possibly be having. I just bought a 99 F250 with the auto trans and 220K miles. When i drive the truck accelerating everything seems great. However, when I let off the pedal around 45mph or so, the truck slows and a pretty rapid pace. It's kind of feeling like the converter is not unlocking because it's an engine brake sort of feeling. I'm new to this trans so is this something normal, or maybe a possible mod the previous owner performed? Any feedback is appreciated!

[Hemicross]

Well, that seems like a good thing, does the lockup disengage when you lightly get on the brake? Does it unlock on decel without brake around 30-35 mph? I would just check your fluid level if you got a yes on the above, but you might have an aftermarket converter, but I'm no pro here so if I'm wrong someone please chime in and let me know I'm full of sheet, lol

[2whlfreak]

Did you ever find anything with your converter lock up problem? Mines doing the same thing.

[ipz2222]

The converter is supposed to stay locked when you let off the throttle. Helps you slow down,( that is why you let off the throttle, isn't it??). Touching the brakes to disengage the tc is about a thing of the past. Most vehicles won't do that anymore.

[2whlfreak]

Up untill recent mine would unlock and I could coast without loosing much speed. Now it almost feels as if I down shift not drastic as a
n automatic down shift, more like a manual trans down shift.