Recently my 92 5.8 E-350 Cutaway van has been doing this weird thing where when I drive at high speeds (in 4th gear) for at least a few minutes, when I come to a stop the van, while I'm braking, kind of shutters and bogs out. It kinda wants to lunge forward but can't because I'm braking trying to avoid crashing into people in front of me.

I quickly started putting it in neutral when stopping and it doesn't do it. However when I put it back in drive the motor cuts off. I pop it back in neutral, start it and drop it in drive and it's fine.

I started to suspect it wasn't downshifting to first and the trans was bogging the truck down, similar to a manual trans when trying to stop with the clutch out. So I then started to downshift while stopping and it stops fine then as normal.

I had scheduled a coolant flush and oil change today so I went ahead and had them do a trans fluid flush as well. He said the fluid was old and dirty but not the worst he's seen. That didn't seem to change my problem however it does seem to shift much better. Any ideas what I should check first or is my trans heading south? I believe it's a E4OD by the way.

 

Yes.. pull the codes, this trans is 100% computer controlled and it generally doesn't do anything it hasn't been commanded to do.

 

Sounds like the TC lockup doesn't open the TC clutch, so indeed it's the same as trying to stop a stick shift without depressing the clutch.
Might sound silly, but are your brake lights working? The tranny gets a signal from the brake pedal that you're applying the brakes and opens the TC clutch. If the switch is bad, the TC clutch keeps closed. This might be a start for your search.

 

That won't do it. It will unlock with vehicle speed, too.

The first thing to check is transmission fluid level. If that's fine then it could be a damaged internal filter, a worn pump, leaking g internal seals, a stuck valve, bad solenoid, or a wiring problem. Getting the codes read is the first step after checking fluid level.

 

Fluid level is perfect. Was before and after the flush. I will check codes tomorrow. Will trans codes show up in the standard code check process? I've done the KOEO and KOER test before to check motor codes. Is it the same process for trans?

 

First, check out this Link.

Read up under the TPS (throttle position sensor)
You'll read that the TPS sends a constant signal to the ECU, which controls the fuel volume, timing and "transmission shift points"

If you want, do pull the codes, and also do the testing of the TPS.
More than likely, that's the sensor that's causing your problem.

I say this, cause I just had to replace mine in the '92, 5.8, E4OD cube van.
I had similar problems, mostly with shifting points, and with stalling at stop lights. Not all the time, just every few days, and then it would run fine, TPS replaced, and no more problems.

 

This sounds about right. I've noticed lately as well it seems to not shift in OD correctly all the time. It doesn't do the stalling thing every time. It was weird because it started doing it only at one particular stop sign between my house and work, everyday. Now it's doing it more frequently. Also I noticed a few times the last few weeks erratic idling that comes and goes. Hopefully the codes will tell me something. If not a TPS is a relatively cheap part and after 23 years it couldn't hurt.

 

I don't think it's the TPS. The OP describes a condition where the torque converter clutch isn't disengaging, which means it's acting like a conventional clutch that won't disengage. The TPS can't cause that because the torque converter will unlock with vehicle speed as Mark said above.

 

I do agree with that statement.

And, something I was thinking about today, was to ask if the brake lights are working in this van? Cause the brake light switch interacts with the down shifting of the transmission.
Also, the brake lights run thru the multi switch on this era van, and additional problems could be caused with that switch.

Still, I would pull codes, and check the TPS thru the link testing.

 

Thanks for all the replies. I haven't had a chance to pull the codes yet but plan on it today. Also I haven't look at my brake lights either but will this morning. Thanks again.