My 98 GMC 5.7 350 1500 sometimes when I get in my truck and put it in drive the motor revs for a few seconds and I have to push kind of hard on the brake then after a few seconds, it mellows out and acts right and run at the normal RPM's it only does this after the initial start up, and never does it again until I restart it. You think maybe it could it be the TPS I just replaced that thing about one year ago from the Zone, I think the warranty was 90 days. There is no check engine light also I have a good scanner tool but all reads normal with it.