For some reason it has started loading up when under hard accelatoring, you have to let off the gas in order for it to shift. I can't find any vacume leaks and I don't really know what else could cause this problem. Fluid is fine and tranny service was done not very long ago.
any advice would be greatly appreciated

 

Does it go into second gear? My 1980 500SE had a problem where it wouldnt go out of 1st at high power untill u lowered the acceleration and then it went straight into 3rd gear. I ended up having to get the whole transmission replaced. Thought I was told if I'd got it seen to straight away it would've been a fairly normal repair, but I let it run like this for about 6 months.
Count the gears carefully, if its skipping one, I'd suggest getting it seen to asap.

 

make sure ur transmission fluid level is where it ought to be. Most likely if it is slipping or wont shift out of a gear, and when it does it is sort of rough, it tends to be the transmission fluid.

 

My car has had a similar problem since I bought it in '98. It won't shift to 2nd when cold unless you rev the crap out it. If I let it idle from cold for a couple of minutes it will shift normally (but hard). It has always shifted hard from 1st to 2nd. I have adjusted the shift cable and the module adjustment on the left side the the transmission. Very strange now - I had the transmission removed to replace the rear main crankshaft seal. I had some seals replaced in the transmission while it was removed. After that it shifted from 1st to 2nd without the warm-up time. Now, after about 1 month it is back to having to wait for the warm up for a 1-2 shift without massive revs. Explain that!