2002 trailblazer 4x4 sometimes does not go into gear
I have a 2002 Trail blazer 4x4 with 105,000 miles on it. When shifting into gear cold or warm the transmission sometimes (maybe 1 in 20) does not go into gear if I miss it engine revs up and then CLUNK into gear. When I notice it does not go into gear If I select another gear it will engage immediatly and when moved back to previous gear it gose in gear as well. This sometimes happens when putting car in reverse or drive. The transmission shifts fine. The transmission fluid was recently changed and is full. I recently aquired this vehicle so I dont know its history except it was not driven for 18 months before I aquired it. Any help would be greatly appreciated.