I posted this problem recently and received some very helpful tips but I want to clarify my problem and ask one more time because my problem still exists.

2001 3/4 ton Ext.Cab 2500 , 5.9 turbo. When the truck shifts into overdrive and if I don't power on through the shift it starts acting as if it doesn't know exactly what to do. No slippage but I can feel and hear it. The tach jumps up and down about 300 rpm like you are slowing gunning the engine. If I exit onto an uphill ramp and slow to 50mph and lug it, it really does it. If I gas it and it shifts to 3rd it's ok. I have been using the overdrive cutoff on slower speeds but noticed recently that it will do it even then, but not as much. I know this is sketch info but it's the only way I know to explain it. I want to take it to a tranny shop but I can't always re create the problem. Cold days seems worse. Any advice ?
Thanks in advance.