I have a 92 Acura Vigor Gs, it runs great most of the time but occasionally the check engine light comes on and it runs poorly like it is only running on four cylinders instead of five, and it won't go above 3 thousand RPM's. I have taken it to three shops and they all come up with the error code 4, which points to the crank angle sensor. I replaced the crank angle sensor, timing belt and water pump but that has not solved the problem.. It still messes up and still comes up with error code 4!! Have you ever heard of this problem? Or do you have any ideas on what the problem could be?

Optional Information:
1992 Acura Vigor GS 2.5

Already Tried:
repaced crank angle sensor, timing belt, water pump