will not start

I've got a 92 Ranger 3.0L that i'm trying to fix for a friend before he comes home from Basic Training. The truck starts and runs fine the first time i start it, but if i shut it off after the engine has reached operating temp the truck will just crank but will not start unless i hold the gas...

I just replaced the alternator today because it tested bad (diode). The truck will not crank without using my jump starter. I also had the battery checked out and it tested good. I seem to have a problem with my ignition not working correctly. When I put in the key sometimes it is not straight...