I had similar the other week. I had just filled up with petrol and the car would not rev steadily above 2000 rpm. It was "hunting" for fuel above 2k. It would briefly rev ok but then cut back to 2k revs in a pulsing way.I think it was dirt in the tank stirred up. It cleared itself after I nursed along for a few miles at 2k max revs. A few brief spells at high speed were tried to help flush the system!
Engine is a ford cvh efi.
I have since thought of fitting an extra filter between tank and pump to intercept any dirt. If next winter sees the car off road for a longer period i may remove and flush the tank.
