Paste
If it's Si-based (and maybe some other too) - vinegar + toothbrush might do, followed by sprinkled bicarb to buffer back to neutral pH, rinse, maybe isopropyl to dry moisture around pins. Vinegar is EZ clean up from bathtub sealants too. (Don't think I'd try acetone for that last..) This might be a PITA to also try on the sockets, with board held upside down! but whatcha got to lose? Squeeze bottle with dist. H20 can ease the rinse.
Still and all - at the temps you were recording.. NO e- likes to run there - MTBF probably suffered some unknowable amount.
Lastly, for insurance and future intermittent-freedom: at local e- tech shop (not Radio Shack) you could look for Cramolin, or one of the Caig nostrums - or .. go to a high-end audio place and buy a sm. bottle of Tweek\ufffd (packaged by Sumiko in Berkeley CA). These do more than 'clean' - the molecule actually conducts under local hi-pressure.. ie It sounds as if your next worry would be that ALL these pins/sockets can conduct despite any residual goop you prolly can't get out of all the holes.
Luck,
Ashton