I am testing the tps resistance. I am getting a reading of 400 between second and bottom tab,but then it drops off in just a few second. If I try to retest right away it my I don't get a reading. If I wait a bit it will do the same thing.

Is the reading supposed to hold at what ever number it reads? Or is it supposed to drop off?

yes it is. i'm also wondering if your dmm is reading right. i'd try to do the same test with a new sensor. tps are known to go out. good call on the fix.