The fuel pressure regulator, if bad can cause just what you've described. Its easy to check, after the car has run a few min. disconnect the vacuum hose at the front of the FPR. If there is any gas in the line or a strong odor of fuel then your FPR is leaking past the diaphram inside it. When that happens it can draw raw fuel through the vacuum line into your intake manifold. I've had to replace mine a couple times so I'm not really satisfied with the quality of GP sorenson replacement I bought, but it was available that day at a local parts store for around $50. Good luck.