I have a 91 Formula with a 305 tpi and it seems that every time I get on the highway and get it up to 70 the service engine light comes on. I have had this checked and all of the sensors replaced. So I was just wondering if anyone else has had this problem?

 

egr removed?, thats probably your problem if it has been. check for a code 32 it is i believe.

 

EGR is the best first guess (and probably the right one). There is also a remote possibility of problems with the EVAP canisiter purge solenoid, or some other obscure possibilities.

Start with the EGR system, including the temperature sensor on the valve base.

 

Will this pose a problem for my performance? Or will it hurt the motor in any way? I have'nt noticed any differance in HP at all.

 

It shouldn't harm the engine in any way, but can cost you mileage and performance. The EGR is used to lower combustion chamber temperatures, so that the ESC can advance timing as much as possible without detonation.