Re: 00 i6 codes P0352, p1391
P0352 = ignition coil control circuit. Does the engine run rough when it happens?
Changing ignition coil normally doesn't help, can be cam or crank sensor related. I would clear the fault first and see if it returns.
P1391= intermittent loss of crankshaft or cam position sensor.
So probably cam or crankshaft sensor related problem.