2002 Chevy S-10 Wion't start

Car was fine. Sat for several weeks maybe a couple of months. Would crank but not start. It would just catch for a second or two and then die. Finally got it started. Let it run for 15 minutes or so. Shut it off. Tried to start it again but it would not. Would only turn over. I noticed the engine was most likely to catch for a second or two if the key was turned all the way off before cranking again. Towed it to a garage, they said the fuel pressure was 30 something and it needed a new fuel pump and filter. I changed both, the condition still exists. Engine turns over, will catch "maybe", for a second or two but will not run. My gut says it catches for a second because of some kind of priming that goes on when the key is turned on, but something other than the fuel pump and filter is limiting or stopping the fuel from flowing. Any ideas? Thanks.