My 2000 silverado 1500 4x4 with 5.3 has a wierd problem that I think is transmission related. When I go from park or reverse to drive most of the time there is a noticeable lag like the tranny is being lazy going into drive. If i give it more gas it sometimes will bang into gear hard so i just easily feather it. Once it goes in drive it is fine and i can drive all over with no problems. It does this most but not every single time. Could the gear selector on the trans be acting up or do I need a rebuild? The truck does have 216,000 miles. thanks