I have a 1992 960 sedan with 118k miles which has an inconsistent starting pattern. Now that the temperatures are significantly colder, my first start in the mornning is no problem at all. It fires immediately and holds an idle at about 600 -700. As the temperature gets warmer during the day the car usually takes 2 to 3 starts before firing and then has a tendency to flutter or surge a few moments before settling down to a decent idle. After driving for a whileI and then letting it sit for 5 to 10 minutes it will also often start and then quit after a moment or 2 requiring multiple starts. During the warm summer days significantly more starts were required to get the engine running although morniing starts were less problematic.

I have provided 2 mechanics with this info and one is convinced that the fuel pump check valve is the problem whereas the other one is convinced that the problem is with the injectors.

As a last bit of info, this car is getting 4 to 5 miles per gallon less than my other 92 960 station wagon with 93k miles.

Where do I go from here and which mechanic is headed the right way?

Any assistance would be greatly appreciated.