1998 Chrysler Town and Country Not Starting

This van was my parents my sister drove it for 5yrs and it quit working for her and I ended up with it. She had a new alt. Put in the day before it quit. The van will not start. When you put the key into the ign. Switch the doors lock. When you turn the key to the run position the asd and fuel pump relay click off and on. The cooling fan turns off and on and the service engine soon turns off and on and will continue to do this till you turn the key off. When you turn the the key to the start position nothing happens. You jumper the starter relay the engine will crank. When it did start the engine would run like someone was turning the power to the coil off and on and the tach would drop to 0 rpm then jump back up. A few times it started and ran fine.