This is all conjecture on everyone part. You need to hook up a fuel gauge at the shraeder valve and see what kind of fuel pressure you have with key on engine off and key on engine running. In order to fix the problem, you got to know what is causing the problem. Throwing parts at it get to be very costly and very frustrating after a while. A fuel pressure gauge set is less than an hour of mechanic's time.

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2006 Infiniti G35
2001 BMW 3.0I E53 X5 Build date 08/2000 SOLD
Lotus Europa 1970 Destroyed by fire
Lotus Europa 1970 S2 Renault Powered
Lotus Type 52 1970 Twincam Webers Powered
PORSCHE 911 Targa 1982 The Garage Queen
Audi Avant donated to Kars for Kids
BMW 525IT Sold
Audi 4000CS Quattro Sold
Jensen Healey Lotus Powered Sold
Opel 1900 Sold
Triumph Spitfire 1971 Sold
Triumph Spitfire 1968 Sold
Plymouth "Cuda" 340 Six pack SOLD