No!@
I would not use acid..you have rubber baffles/seals in there and there is no telling what the acid will do. If your baffle is torn the FD won't work right, if seals are blown out it won't work right.. there are VERY fine orifices in the FD (did you have a look @ the pics on my page) so they may be clogged &/or corroded.
If any DIY'er has had luck reviving their FD on their own I would love to hear it.
Jonathan