Dealer should have them or go down to your local hardware store and pick up some M6 bolts of various lengths. M6 will have a 10mm head which is probably what yours were, very common size. Yours are probably between 10-15mm long for the thread length.
Measure the thickness of your TPS where the bolts go through. Then take a small screwdriver and insert it into the mounting holes until it bottoms out. Put your thumbnail on the screwdriver against the hole then take the screwdriver out and measure how much of the shaft went into the hole. Add that measure to the thickness of the TPS mount hole, subtract a few mm, and you've got your thread length.