I have a 97 chevy blazer 4.3 liter v 6 driving down the freeway about 5 minutes truck dropes out of gear. anti lock lite comes on in the speedometer goes to 0 . Only gears that works is second after that wont shift unless I stop shut it off for a sec than works for like 30 sec. Does the same thing after that. Its seems like it only does it when it gets hot. So I changed the pan gasket and filter. And added 5 quarts of trans fluid. Does same thing and ideas?? Thanks for your help!!!

 

Try changing your VSS. I'm fairly sure that when the VSS goes, it causes those symptoms. Maybe someone else can confirm?