incorrect operation of choke choke not shutting off after warm up
Having the speedometer jump and the engine stall in the 1994 Jeep Grand Cherokee Laredo could be a problem with the idle and the transmission. The transmission slipping can cause the speedometer to jump.
Do you mean the rpm's on the tach? The bike should not run down the road at idle. At idle, in gear it should jump forward and die. If not, the idle is too high.
Could be a idle control sensor but your best bet is to get the computer checked and see what codes come up.
idle air controler
Could be a number of things. Does it jump when you are driving it and parked? It could be an idle air control valve or even a throttle position sensor, it could be misfiring also. My t/a did the same and it turned out to be the idle air control valve.
I'd suspect the alternator. You can have it checked at most any of the chain parts stores. FriPilot
I would check the idle air solenoid on the intake manifold
If you were to be dribbling down the court and you want to come to a stop you would jump up and come down on both feet.
Timing belt. misfiring engine
The Subaru engine could have a vacuum leak, bad head gasket, stuck choke, or several other things causing the problem. Any of these could give problems then ease up as the engine warms up.
Vacuum leak ?
I had a similar issue on my 91. There is a single blue wire on the throttle body. Pull it off and see how it runs. Mine worked fine without connection.