Mid boost popping/misfire HELP

[Ni$$@n240]

The car will run fine off of boost just cruising around but when you get to 6psi and around 3500rpm's it acts like it misfires or backfires. I have checked all the intercooler piping for leaks and cleaned the maf.Changed the plugs and even tried swapping each coil one at a time. Earlier in the year It had a surging issue which I replaced the coolant temp sensor with a used one and fixed that. Now Im wondering if I should have just got a new one?
The car has the following done to it:
Front mount ic
newer turbo (stock)
isis electronic boost controller set at 12psi
enthalpy tuned ecu for the brian crower stage 2 cams, stock ecu and injectors at 12 psi.

Car ran great on the tune all summer (after switching the used cts) then out of nowhere starts doing this.
Im thinking its either the coolant sensor, or the battery.
Any suggestions would be appreciated.

[PyR0NiAk]

Why would you think it's the battery?

[Ni$$@n240]

Why would you think it's the battery?

Because I know Nissan outboard motors will run funny when you dont have a good battery.
Besides the fact the battery doesnt hold a charge for more than a day or two. Its one of those small buddy club racing ones. I dont trust it and even put water in it before and its supposed to be one of those maintanence free type.

[Sugar]

Alternator should compensate for the battery if its running. I could see it maybe idling bad with a bad battery.

Check ohm's on the CTS. See if it's in check with the FSM. Even though they can still be bad, so might as well replace it I guess.

[Ni$$@n240]

Alternator should compensate for the battery if its running. I could see it maybe idling bad with a bad battery.

Check ohm's on the CTS. See if it's in check with the FSM. Even though they can still be bad, so might as well replace it I guess.

Yea thats what I figured. Since its not going to be driven this winter we might as well recocate a bigger battery also.