hey mate,
I've an r32 and I had a problem that fits your description. It was caused by blocked injectors and fuel lines. Got them cleaned and all good now. May not be your prob but i'd check the fuel fillter and see how dirty it is. If there is dirty, sluggie stuff in it take it to a proffesional and get it looked at.Deffinatly sounds like a fuel problem though.
Hope this helps
Glenn