car wont crank unless jumped, battery dying, low idling ( sometimes at 100 rpms) and then stalling, driving at 50mph and throttling and drops to 0mph

[cruisingalong45]

I have this long list of hopefully closely correlated problems as they all showed up at once. (background info) I just bought this 1994 land cruiser (I'm 19) so still new to this world especially the land cruiser world... anyways, I was getting ready to leave one day and car would not turn over at all and I discovered that is was do to an aftermarket alarm that I eventually flipped the switch to and the car started, but only with a jump. it idled very low and and I had to make it home most of the way in neutral idling very high so the car didn't stall. as I was driving home a few things happened, 1- I would be driving and the gauges for the rpm and mph would shoot up and down. that then stopped and they sat at the correct levels and when I throttled they both shot to 0. and then they both sat at 0 for the rest of the way home, while I was driving the battery level was going down and I barely made it home before it died. been sitting in my driveway where I messed with the alarm system, the battery, and the fusible link. so having said that, are these common problems together? and has anyone got any advice?

 

[jonheld]

I have this long list of hopefully closely correlated problems as they all showed up at once. (background info) I just bought this 1994 land cruiser (I'm 19) so still new to this world especially the land cruiser world... anyways, I was getting ready to leave one day and car would not turn over at all and I discovered that is was do to an aftermarket alarm that I eventually flipped the switch to and the car started, but only with a jump. it idled very low and and I had to make it home most of the way in neutral idling very high so the car didn't stall. as I was driving home a few things happened, 1- I would be driving and the gauges for the rpm and mph would shoot up and down. that then stopped and they sat at the correct levels and when I throttled they both shot to 0. and then they both sat at 0 for the rest of the way home, while I was driving the battery level was going down and I barely made it home before it died. been sitting in my driveway where I messed with the alarm system, the battery, and the fusible link. so having said that, are these common problems together? and has anyone got any advice?

If you have a standard flooded cell battery, it's done. Once it is discharged, it likely won't take a full charge anymore.
All of the issues you stated are related to a failing power source.
I would replace the battery and fusible links as a first step (90982-08264 available from any dealer)

Make sure the battery terminals are tight.
Have your alternator tested, as you've put a heavy load on it running with a depleted battery.