Did you try checking for codes?
this can be done by cycling the key 3 times.
Key on - Key off - Key on - Key off - Key on (let key in the on position)
Watch the "check engine" light, as it will start to flash
You should get something like this:
flash-[short pause]-flash-flash (that's a code 12)
Then a [long pause]
flash-flash-flash-flash-[short pause]-flash-flash-flash-flash (that's a code 55)
and so on.
Check and report back with the codes and we'll go from there.
Oh...and only cycle the key to the "on" position, not the "start" position each time!!!
