Ford Econoline with a problem

1999, Ford Econoline E150, automatic, 6 cylinder, 75,000 miles.

Before I bring it in to be checked, I would like to see what you might think. I realized that a description of the problem is not like you actually driving it. I'll give all the information I can.

I have put on about 150 miles since I retired about a year ago. When I drive it at 30 mph I can feel it "buck" or "jerk" and this last time I heard a 5 second sound like crashing metal. As the speed increases, so does the problem. I also noticed a loss of power particulalry going up hill (20 mph max.). The problem has gotten worse each time. There also was a time when it started out with the problem and then it disappeared as I drove further.

In neutral with engine revved, it is fine.

The only opinions I got from my neighbors are: catalytic converter, parking brake or transmission.

Thanks in advance for any insight in diagnosing my problem.

 

No Pro...but I'd be checking driveshaft and Ujoints for the buck and noise. Esp if its shifting through the gears ok. Fluid levels ok? Trans I mean?

Don't know about that loss of power thing, could be unrelated.

Parking brake would cause sluggish movement taking off, not in the middle of a drive (that I know of). Also your rear wheels would be smokin hot in a very short time. Can you coast or roll with the trans in Neutral?, prob not brake.

Sounds like its after the engine, probably. So Trans and after.

Shadetree mech only here..