First time I noticed a problem was after a 45mile trip when I was waiting at some lights. I gave it some gas and there was no drive for about a second and then it jolted a bit and drove away normally. I had been stuck in traffic for upto 30 mins with the engine running all the time about 20 miles earlier but didn't have any problems til I was almost home.
A few days later I went for a drive and the box was making a whirring sound on accelleration and shifting quite hard and later then usual. After about five miles it occasionaly lost drive for a split second.
A week later I go for a drive and get the same noise and again after about five miles it begins to lose drive but this time alot worse and I didn't think it would get me home but thankfully it made it with a lot of revs and not much speed.
My drive is quite a steep incline and the car managed to get up on the drive with the speed I had built up on the approach. I switched the engine off and went indoors for less than five minutes and then went back to the car and started it up to put it away and it drove up the drive with no problem at all

I've checked the fluid level with engine running and in neutral after running through the gears and its just a fraction over the max when hot. I'm also using dexron III
Anyone had a similar problem before? Gearbags are not really my specialty so I'm at a loss on this one.
Any info appreciated.
Cheers!
383ci and 727box by the way.