Originally Posted by
Jordan T
just rip the pos 1.6 out and throw in the 1.8. the crank pulley is gonna give out sooner or later anyway and it could have already by the way your problems sound. if the keyway has givin in it can throw you timing off ever so often and make the car break up and run sluggish, not to mention bend your valves.
The keyway issue only affects 90 and early 91's and generally only if the key wasn't re-installed correctly after a timing belt change. Also, the Miata engine is a non-interference engine.
Have you gotten water in the car lately? The ECU on your car is under the front of the passenger floorboard. If water got in the ECU it could also cause issues.