E40D issue

[bburrito]

I have been having some issues with my E40D recently that I am not sure exactly what is going on. In 3rd and 4th gear I have noticed sometimes that when I am accelerating, particularly up hill, the transmission will start making a lugging sound and the whole vehicle will start vibrating weirdly. If I back off on the accelerator just slightly, it will go away and the vehicle will still accelerate just not quickly. If I try to push the accelerator any more, it comes back, but I release a bit of pressure and it goes away. Has anybody ever heard of anything like this? 1st and 2nd have no problems at all.

[Alaskapsdvan]

Sounds kinda like what starting going on with the AeroStar that I had years ago just before the trans stopped all together, for the second time.
I was not going to spend another 1700.00 so out with the Aerostar and bought the 1996 E350 gas and drove it almost into the ground.

[VISIONQUEST]

may be that your tq converter is locking up like its supposed to, so take it out of OD dont lug it up hills . your probably doing around 1780 rpms got a tach on it ?