2003 Chevy Astro multiple issues

I multiple problems with my Astro. The brake lights (both light) come on periodically but doesn't affect the brakes. The mechanic figures ita sensor but doesn't know which one. The remote locks just started to work periodically, you think the vehicle is locked but it isn't. I tried to lock the vehicle sitting in it and the lights come on and goes off the locks start to engage put quits before they lock. Then starting the vehicle and putting in drive the transmission doesn't shift properly, it revys up then shifts as you drive. It only does this right after starting the unit. If you pull to a stop sign and take off it shifts properly.