Sometimes you can't get the TPS to adjust within spec properly. When it's adjusted to just under .5 are you having any problems?
Another "TRICK" I learned when adjusting the TPS voltage is to bend the metal tabs on the T-Body that the sweeper sits in. Then try adjusting the TPS from there. You have to be VERY careful when doing this because if you damage the metal tabs, you might as well toss the t-body in the trash.
Good luck with this, let us know the outcome.