Fuel Rail M104

[thauber]

Still tinkering with my 93 300E 2.8. I have had a starting problem for a little over a month now, sometimes starting instantly, other times taking a couple minutes of trying and having to press the accelerator. But here is my question.

I put a new fuel filter on the car because when it blew the headgasket awhile back, it sat for 6-8 weeks before I had the time to conquer that quest. So I figured it would be wise to install a new fuel filter. After putting it on, the car started instantly, much to my surprise. I drove it off the ramps, turned it off, and cranked again. Back to the normal hard to start. But it got me thinking. That was about a week ago. It has been less and less often that it takes more than one try to start the car, so I pulled out the fuel rail gauge again(had checked it months ago and had 60psi). When key is turned on, it jumps to 75ish area for just a second and then drops to 55. Crank on the car and it stays between 62-64psi and stays there with car running, just shaky. Let it sit for 15 mins and the pressure would drop to around 35psi. Bled it off and repeated the test 4 times always with the same results and the car starting easily. Is it likely the culprit to be the pressure regulator has some "trash" messing with the valve or possibly warped it, and by releasing the pressure on the rail it seats back to where it is supposed to be? I'm hoping this seems logical to someone other than me, because a regulator isn't an expensive part.

Any thoughts and suggestions would be great as I am sure this will help others I've seen come through this forum with similar symptoms.

Forgot to add that when the car is running, it drives great, no loss of power, but has stalled on occasion sitting at a stop while in (D).