2001 Infiniti I30 starting issues

Neither the starter nor the generator can burn each other out. If you have intermittent slow cranking, that is due to not enough current flowing to the starter, and that is due to a bad cable connection or a run-down battery. Next time it acts up, measure the battery voltage before you go any further or wear the battery down further. If it's fully-charged it will be 12.6 volts. If it's down to 12.2 volts, it's okay but it's discharged. Charge it at a slow rate for an hour. Next we have to determine if there's a drain that's running the battery down or if the charging system is not recharging the battery while you're driving.

If the voltage is close to 12.6 volts but it still cranks slowly, measure it again while a helper cranks the engine. Put the meter probes right on the battery posts, not the cable clamps. Remember that voltage. It has to stay above 9.6 volts during cranking. Now move the meter probes from the battery posts to the cable clamps and measure again during cranking. You should see the same voltage. If it's significantly lower at the cable clamps, take those connections apart and clean and tighten them.