What is liter size of engine? If you have that spider fuel system, That system is noted for problems. The start-up fuel pressure can be critical, key on engine off, 60--66 psi. Did you use a fuel pressure gage? In the past, did see service bulletin about fuel poppets sticking. That was usually the first start of the day after vehicle sit over-night. Once it started the vehicle would usually do fine the rest of the day. To fix the fuel poppets there was a cleaning procedure, The procedure I saw was a shop procedure.
There could be other issues? How long since a tune-up? Any applicable trouble codes?