With a failed ALDA it can limit rack travel to the point injection is low enough to barely accelerate the engine, let alone an entire vehicle.

Here, I removed the ALDA and made this video to demonstrate.
http://www.youtube.com/watch?v=m2wcLGIrevs

I talked to my indy today, he believes it had to be the ALDA. All he did was replace it and readjust the linkage, now I have plenty of power. It appears that the failed ALDA was somehow limiting full "throttle" performance. He didn't disassemble the old one.

How about the obvious answer? Tank screen?

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Nope, replacing the ALDA fixed it. I was pretty sure it wasn't the screen when I removed the first filter and a good stream of fuel ran out.

Yeeeeeaaaah about that I think I am having similar issues but I am going to search help from archives here and from other threads. I partially see where the ALDA gets input and what that input does and effects. I hope it is as simple as cleaning crud and soot.

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That's excellent.

Apparently, the ALDA has significantly more range than I had anticipated...........in its capability to restrict the rack. Although it's not apparent in normal operation, under a specific failure it clearly can cause the OP's issue.

Thanks for the video.

That is a similar, but more extreme, example of what mine was doing when I lost power; I could move the linkage about half way with very little change in engine speed, then it would finally start responding. It was acting like the ALDA was somehow "stuck," holding that plunger partially down. Good video.

Over a period of time I have observed far fewer injection pumps are being changed out. I suspect this is just a result of us all getting more familiar with the external issues.

Even the alda and relief valve I consider to be external even though they are an integral part of the pump almost. At one time I remember a lot of posts to the effect that they had changed the injection pump and the problem remained. Just not generally happening anymore. This is not a bad thing in my opinion. Experiences like yours add to the common knowledge lore.

There has only been one other I can remember that was very simular to yours in that there was little actual throttle response. It too was the alda. As these cars continue to age this is the type of thing we will see more of them.

I agree, actual IP failure are very rare on these engines; I actually had one fail with an internal leak.