I need to repair my Chinese Stealth suit (modded so it's back to being overpowered)...but I can't find someone to repair it.

Try maybe, the NCR Mojave Outpost? You sign paperwork, they repair items.

Jacobstown - calamity
mick and ralph's - mick
Inside vegas strip there are several who do it
Brotherhood of steel safehouse - paladin sato
the fort - dale barton
188 Trading post - Samuel Kerr
and more.

Thanks, Mojave Outpost had it, too bad my repair is low, only got like 3/4ths repaired!