Is this Transmission Bump?

I have a '93 Ford F150 with an automatic transmission, and occasionally (Once or twice a trip), when the truck shifts up (Never happens when shifting down), if feels as if I'm being kicked forward a little bit...I don't think it's backfire, because there is no loud pop that I can hear of... Could this be engine misfire or a transmission bump? Also, what do I need to do to solve this? Thanks a bunch in advance!