how to check if fuel pump is working

You have an electric fuel pump in the tank. If you take off the gascap and listen at the gas filler with a helper switching the key to RUN, you should hear the pump runnig for a second or so. I once had a car that stalled going around left turns and it was due to water in the tank. sloshing into the pickup area when in a turn. Find a Mitsu specialist. Here's a directory link for you: http://repairpal.com/mitsubishi-repair-in-visalia-california