2000 misth eclipes it just shut down on me on the highway now wont start what could it be?

get a new ignition relay~ https://www.google.com/#q=2000+mitsubishi+eclipse+ignition+relay Insure that the relay has good ground....clean the 1/0 battery cable as it attaches to ground insuring a solid 12V to this device which....only keeps you runnin'

sorry about the china reference...you could get a denso if you shopped for one~

How long since your timing belt was replaced? These cars are known for timing belts issues if not properly maintained. Also if it does turn out to be a timing belt issue do a compression check cause you might have bent some valves if timing belt jumped or broke.

agree with the timing belt post.