I turn the key to the on position and the dash lights up, turn it to crank position and nothing happens. The battery is good and I've checked the grounds, replaced the starter and ignition switch, problem still exists. I can jump the starter and it will run for a couple seconds and then die. Prior to this problem sometimes when I would turn the key to crank position it would delay a second or two before the engine would turn over. Any suggestions of where to go from here?

 

Neutral safety switch would be my guess. Is the gear shifter worn or has slop? Hold the shifter hard into park, or put it in neutral then see if it cranks.

 

not sure if the NSS would cause it to stall after running. in my mind the NSS would prevent it from cranking then if you did jump it it would just stay running. have you tried swapping relays?
have verified your getting signal to the starter?
can you get someone to turn the key to "start" and try to feel or hear the starter relay click (its called "crank relay")

also theres a fusible link
as you can see in this picture the key sends a signal to the ecm to crank and the crank will ground the "crank relay" and then the starter will get power.

 

Switch won't keep it from running, but won't allow it to crank. I suggest put it in neutral as the slider from the key switch may have slipped, or the shifter is worn. I remember in HS if we had this issue, we would simply bypass the NSS, I'd not however recommend doing that.

 

im with you, i understand the neutral trick and have used it a few times in various vehicles. even while cruising down the road ive shut a truck/car off and had to restart it after putting it in neutral while still going down the road. the stalling issue is what gets me but maybe since it has to go through the ecm and the ecm isnt getting the signal to "start" maybe its turning itself off kind of like an anti-theft