Subject: 94 mighty max misubishi v-6
Question:

what causes it to idle slowly or shutoff. runs fine on the
highway, but when I stop it idles very slowly or shuts off.
It's a four speed 4x4.
Answer: Ed
There's a number of causes for this:
- Clogged air filter
- Clogged fuel filter
- Clogged EGR valve
- Clogged PCV valve
- Improper ignition timing
- Dirty throttle body
- Malfunctioning Idle Speed Controller
- Weak fuel pump / fuel pump regulator
- Worn spark plugs / plug wires
- Worn distributor / ignition coil
- Failing alternator and/or battery

You may just need a full tune-up to better narrow down the cause for your problem. Hopefully, it's just a maintenance item that needs to be replaced.
Good luck!