1995 Chevy Lumina Quit running

My 3.1, Lumina APV quit running. Here is a brief history leading up to the final sad event.

95 lumina apv, 3.1, 177K miles:
It started running poorly about a month ago. It would not run smoothly at speed and bucked when trying to cruise and backfired when decelerating. I read the troubleshooting section of my manual and decided it was a bad gas filter -- sepecially the trouble started immediately after filling the near empty tank. It seemd to clear up.

Yesterday, it started again (160 miles aftrer aparent fix), and me 55 miles from home. So, I took a chance. This is my observation of what happened along the way:

Vehicle would idle at lights and accelerate well enough, but sluggishly. Once I reached speed I relaxed the accelerator and the vehicle began to buck with the backfire when the pedal was released. I discovered I could keep it from "bucking" by accelerating and allowing it to decelerate, and repeat the process. I let the speed drop to 60, then accelerate back to 65+. Somtimes I could get it to run well enough at 65 to use the cruise.

Eventually it changed. About 10 miles from home it began to buck and slow. I could keep it running by holding the pedal to the floor. Gradually top speed went from 65, to 35, and then held at 25 for about 4 miles. Then all I could get was between 10 and 15 mph for the duration of the trip.

Pedal to the floor, the engine barely ran. I could hear it hear sucking air, and it was shaking. It stopped, but restarted -- barely.

Changed filter again today. No change
Fuel at Throttle body and coming through injectors.

Won't start. Fires, but will not stay running when key is released. WIll only fire when pedal it held to the floor -- like in the good ol days of carburators.

You think I could put a carb and distributor in this pig?

The engine has a new distributor, coil, plugs and wires, and is getting gas.

It's got me beat, although I finally got a "Check Engine" light this morning while trying to start it. Din't have one all the way home.

Fuel pressure is 10 psi which is within spec.

FOund out my local O'Reilly's Auto Parts loans out a hand-held diagnostic unit, but I cam up NO Error codes.

Read some more, and tested the MAP sensor. Had 5.13 volts as required, but did not drop voltage with vacuum applied. So, I replaced that. Now it idles real nice, but nothing more. Actuate the throttle and it stalls and back fires as it dies.

However, Since it idled so nicely, it ran long enough to bring up the "check engine" light, so It's back to O'reilly's for the didagnostic tool. Maybe it will read this time.

I'll be checking the TPS voltages tomorrow, regardless.

I can see the EGR moving, so it's not stuck.