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[91boz]

I am helping a friend with his 90 4AFE Corolla. The problem is intemittent hard starting especially first thing in the morning. The first problem is the engine will turn freely like the timing belt is broken and when this happens there is no spark. Other times the engine will crank but will struggle to turn over like the timing is way off but this time there is spark on all cylinders. Once the engine starts up it runs fine and the problem goes away untill the next morning or sometimes it starts right up!
The computer, distributor and map sensor was all swapped out when the problem was present so they are not causing the problem. The timing belt was replaced along with the water pump but the problem was already present before replacement. Anyone have any idea as to the cause of the problem?