The TPS's made by Toyota are actually some of the best on the market. The black stuff is resistive ink printed on a ceramic substrate. They're baked at a very hight temp. but I'd be carefull what used a cleaning solvent. If you wear any of this ink down, the resistance goes up. The contact springs will usually wear out before any damage to the ink is done. The contact springs should have a little radius to them, if not, flush the whole TPS down the turlet. Hope this helps a bit.

2000 Tacoma SR5 - Bone stock 'cept a little bling.
2000 Tacoma SR5 - Bone stock.