Have you checked to see if the security system is shutting you down?
Try the fuel pump relay
the ignition control module could be the problem
The Ignition Coil is the one that cause misfire or Spark Plugs
Crank sensor has failed,Ignition control module (ICM) has failed,Bad ignition coil pack,
the climate control electric connect is unplugged or loose
replace your head light switch
two things..the ignition switch its worn out and need replacment or the selenoid inthe starter its going bad, need to replace starter,one or the other,,
p1399 is manufacturer control ignition system or missfire, this code could be coils,plugwires, or plugs,
http://www.therangerstation.com/tech_library/TFI_Diagnostic.html Heat
i did have same problem on my 95 aurora i have replace ignition coils sparkplugs and wires that solve my problem
check the idle control valve not that hard to replace and inexpensive
broken dccv... look for dual climate control valve in the answers...
Head lights on?