2003 Focus, hesitates

My 2003 2.0 Zetec focus wagon has a problem when I hit the gas from a dead stop. The car hesitates for a second or 2, like it's not getting enough fuel, then it revs up OK. Not all the time though, about 1 in every 5 stops. Once it's moving, there's no problem, you can accelerate just fine. I replaced the fuel filter and added fuel treatment. I also saw it had a real bad valve cover leak that had flooded all the spark plug wells. I replaced the gasket, plugs and wires, but it didn't seem to make a difference. Using a scanner, I monitored fuel pressure at idle, it was about 38.5 PSI. When I hit the gas it it went up to about 40 PSI. Any ideas? I think maybe the ignition module/coil might be going out, but don't want to replace it unless I have to.

Key on engine off 35 to 45 psi
engine running 28 to 45 psi

There was a recall I believe about faulty fuel pumps, which you might want to check on if you havent already. Also there is a fuel sensor on the rail/engine and a fuel module under the back seat, which might be of significance. Good luck.

Fixing the oil leak and replacing the plugs and wires seems to have resolved the problem. Better mileage now too. Thanks.