[WestCoast]

coils have nothing to do with the engine turning over slow, I would first have the batt checked, make sure all batt connections on batt and cables are clean and tight, then make sure the ground to the engine is clean and tight, no rust under the cable between it and the engine, , if that doesn't cure the problem I would then check the solenoid and starter, make sure you don't have the ground hooked to an exhaust bolt, heat causes a bunch of resitance `and lowers voltage to the starter, make sure you have the big 6v batt cables not the skinny 12v cables