I had to rebuild mine about a year ago and I have had no problems with mine. What all did you do when you rebuilt yours..... Mine I had to clean it completely after all the guts were out I soaked it in brake fluid and then after that I used some steel wool to clean out the inside mine had some surface rust in it, so after cleaning it out thoroughly I used some brake cleaner to get all the crap out and basically spent about an hour making sure that it was REALLY clean

then I used the rebuild kit and put it all back together and I have had no problems with it since.
I know that you might have done all of this but I would suggest trying to clean it again and if it doesnt work again then I would try to find another one, which might be pretty difficult unless you find someone on here that might have one left from their V-8 swap
just my two pennies
Later
Husker