I'm having the same issue -- cranks for a long time before firing up. New plugs, wires, A/F sensor, air filter, battery; cleaned MAF, throttle body, all sensor & wiring harness connectors. Installed fuel pressure gauge -- FP within FSM specs for pressure and leakdown. Have used Seafoam both thru the PVC hose and in the fuel tank several times. Compression is w/in spec for all 6 cylinders

I think the only thing left is to remove the injectors and have them professionally cleaned.

Other than that, I've exhausted all my "good ideas." Frustrating.