Similiar set of circumstances on my 95 contour turned out to be blocked Catalytic Converter.

Tim Raymer
>Ihave a 1994 ford ranger with 2.3l
>4 cylinder engine. i have replced
>the egr valve, egr relay and
>now is giving me a mass
>air flow error when i read
>the computer. the engine makes a
>reving noise and doesn't have good
>power. my gas milage has gone
>from 20 mpg to 15 mpg.
>also if the vehicle stalls when
>backing up i can't start the
>vehicle and the computer gives me
>an open fuel pump relay. if
>i let the truck sit for
>about 10 minutes it will start.
>if anyone can help me i'd
>appreciate it. thanks pat