Why would a Chevy suburban not move in reverse and when in drive it has to go to 3 RPM before changing gear?

you have tranny problems. need to get it fixed. after getting it fixed or when, add a trans. cooler/radiator. This will make, if your engine over heats, your tranny didn't. there are alot of little membrains seals in a tranny. when the engine over heats, so does your tranny and these seals melt. after a few months you will need tranny repair. tell me, has your sub. over heated in the past 6 months? I have been through this already afew years back. Had my tranny repaired {$1600} put on a cooler {$39} and have had no more problems. This info. was given to me by a tranny spec., good friend. Like he told me, they won't let you know this at a shop.