Problem with a electrical issue

Problem with my radio and aftermarket sound system subs hit hard sometimes and then sometimes don't hit hard enough

 

Not enough details.

I'm tempted to say "bad ground", but you only shared 19 words with us, haven't told us any info about what hardware you have, how and where it's installed, what gauge power wire you used for the amp and how that wire is run and where it's fused.

Give us some more details.