Are you having to do an "EXTENDED CRANK" to get the engine to fire off??
If that the issue,,,when the engine is cold, check your fuel pressure. When you turn the key to on, the pressure should come right up to spec. If it doesnt, your expierencing fuel drain back.
The anti syphon check valve in the fuel deliverly system is allowing the fuel in the fuel line to drain back into the tank. It takes a few trys to build up pressure, thus, the extended crank problem. Turn the key ON & then OFF a couple of times and see if that "HELPS" correct the extended crank issue. if it does, replace the check valve.