1995 Ford Ranger 1995 Ford Ranger won't stay running

I have a 95 Ford Ranger with 214,000 miles no prior problems to speak of until the other morning I went out to start the truck and it was dead, I jump started the battery and noticed the battery guage jumping a little (I had not noticed this in the past) I let the truck run for about 15 minutes shut it off and tried to start it again and it was still dead (would not turn over the engine.) I have had the battery tested as well as the alternator and both have tested as being good. I have replaced the solenoid and still can not start the truck. I can jump start the truck but it will not restart once I shut it off unless I again jump start it. If I turn on the headlights after jumpstarting the truck it kills the engine. Any help with what this might be or what I should check next would be appreciated. I really don't want to take it to a shop for something that may be an easy fix.