93 coupe CKP code 4

okay ive got a slight problem, i got a CKP code 4(crank position sensor) not too long ago. Ive replaced the sensor with a new one and reseted the ecu. I can drive all day in stop and go traffic without the engine light comin on but as soon as i get on the interstate and put it in 5th gear the check engine light comes on. Nothin happens when it comes on but its just buggin the hell out of me. anyone with answers¿¿