Weird, Possible Transmission Issue

Alright, this issue is weird and so far, Google hasn't helped me figure out what's wrong.

Background:

Truck is a 1999 Ranger, XLT Supercab, 4.0L V6, Automatic, 4WD, with the suicide doors. 148K Miles.

Over the summer it had it's transmission fluid and filter changed, was all clear, no metal or anything. Recently it got a new battery and either the fuse on the radio died or the radio has a short, drained the old battery, and died... I'm not investigating that until Spring (when I can risk lower battery voltages and walk to the auto store).


Last week of December, I take the truck for it's inspection. I have the usual things done on top of the inspection: Oil Change, Tire Rotation, Check the 4WD Hubs (I had the vacuum lines fail once, I always ask them to check before winter sets in). Truck passes without an issue.


The Issue:

I go to drive it home, and it starts to make a sort of oomf and lurch when I stop. The weird thing is, it is not every stop or every other stop. It seems to be almost random. Hard stops don't appear to experience the issue. It feels very similar to popping a clutch when slowing down or getting rear ended... Or having a heavy load shift and ram the back of the cab.


Truck sits for 5 days before it can go back to the garage. If they broke something, they're paying to fix it. I had figured "ok... it's gotta be the brakes." I go to put it in drive to take it back, and it takes forever to get in gear, there comes our biggest 'oomf' sound yet, and one hell of a lurch forward.


Garage checks the brakes... and for added measure looks over other things, slip yoke and all... No sign of a problem. They tell me it's the transmission. I got the MAF cleaned... because some guy in Kansas had a lurching problem that went way after a MAF cleaning.


Drive it home... it's still as bad as before.



My last trick was to unhook the battery. I have a thought "well, it's an electronic shift, it has parameters... has it got a bad parameter?" 15 minutes later, hook it up again, and it slams into first again, but the lurches/hops start to go away.


Now, it still does it, but it's less severe. I have to pay attention to notice it. It's still audible. It seems to be worse when I get up a really good had of steam and come to a stop. In one case, I let off the gas on the highway after a harder take off, and it slammed a bit into 4th.


I suspect there's a solenoid(s) starting to go, but it hasn't degraded enough to throw any codes. I don't believe it's the U-Joints, as it doesn't lurch on forward or backward movement, only stopping.

That does sound like your transmission to me. I've never heard of one doing that exact thing, but that doesn't mean it hasn't happened. Almost like your torque converter is screwed up, or the bands are malfunctioning somehow. I don't know, as I'm not a trans guru.

Chris

It gets weirder... It's been getting better and.... I don't know what to think. I just had it out for a run today, cold as hell out. It didn't go into gear when I shifted it the first time *BUT* the whole truck is coated in ice, so I think the linkage might've been frozen. Second time, smooth shift into gear. It behaved fined.

I don't *think* it's the TC. If it were that, I would expect it to be having issues all over the place. I'm still thinking valve body.

My plan is more or less to drive it until it throws a code. I can't quite afford to go poking around (and it is 20 degrees out)..

Yeah, I don't know.. I have heard that if you haven't serviced the trans on the schedule Ford recommends, flushing the tranny can dislodge sediment/gunk and clog up the valve body. I know a friend of mine with a Dodge 1500 says if he doesn't flush the trans every 40k, it acts all kinds of funny, so not sticking to the maintenance program isn't only a Ford problem. Let us know what you find!

Chris