Let's try this again, hit the wrong key first time. Have had similiar problems, cured it on the race car with a PA servo, about 100 bucks. Could be other things that Ricky said, if the clutch's are worn it creates too much clearance in the drum and takes longer for engagement. Also C4's are noted for valve body leaks, have you had a pressure check done? I feel that it's in servo band apply transition. But it's still a guess without a hands on look see. A good adjustable modulater could help, should be able to get the screw in one at a trans parts supply. TPS in Little Rock has had them. Will try to get # for it and price. Just my 2cents worth.