My granddaughter has a 1995 F15 6 cyl 5 speed that cranks but will not turn over INTERMITTENTLY. We have had the starter, altenator, fuel pump, battery and a chip in the computer replaced and we still have this problem of intermittent refusal to start. It can go for days and start right up then the next time you try it will crank but will not start. I had it towed to a repair shop the last time (they replaced the computer chip at a hefty cost) but obviously did not fix the problem. Does anyone have any idea what this might be. I don't want to take to the shop again, pay money to have them "fix" it and then have the problem reoccu

Ah, have you replaced the fuel filter?

If it's a 1995 Ford F150, I would replace the Ignition Control Module (ICM) and coil. Easy to replace yourself. ICMs are particularly problematic.