'98 Astro Van dies while driving ....

Hello, thank you ahead of time for any suggestions offered. Here is my problem. Last Friday I noticed my van labored to start (this after it starting fine all day long). I drove around the corner to the store and when I got back, it would not start and the symptoms indicated a bad battery. I had the battery jumped, van started and as I was driving home several lights on the dash panel came on, a buzzer came on (like the ignition buzzer) and even though I was rolling to a stop, the MPH guage was going nuts, jumping from 5mph to 40mph. At this point as I was rolling to a stop, the van died. The battery seemed to be dead as all I would get is a weak buzzer sound and dim lights on the dash. I cleaned the battery posts and it fired back up and seemed to be fine for a whole week until today. Same thing all over again, I could start it but had to keep the gas pedal pushed in high RPM's to keep it going and eventually it would stabalize and stay running. I don't think it is the Fuel filter because of the fact I do get a week starting signal at times. I went out to test it just now and although it was weak on cranking, it fired up much easier without dying and no gas applied. Any ideas on what is going on here ? Any help would be greatly appreciated as I am not mechanically inclined whatsoever and have no clue what to look for.

Thank you,
Bob

First I would look at the battery and charging system.
The modules on those vehicles need at least 10.5v to operate..any less than that, chaos insues.
The alternator should keep your vehicle at operating voltages while the engine is running.
Take your vehicle to your local autozone..they will check it for free