When driving, when I throw into neutral, it idles weird, like 500-1000 rpm up and down. Also getting reallly bad gas milelage, car smells more like gas then before. I have a turbo gsr.

Can spark plugs be the issue?

 

could be a tonne of things
what kind of fmu are you running?

 

Hondata s300

 

Check your iacv. They tend to cause a fluctuating idle.

 

any codes?

 

what about the gas getting eaten? can drive 20 miles and it eats 1/4 tank, never used to do that.

 

do a tune-up if it been awhile.

but it sounds like a bad map sensor or O2