Are you waiting for the engine oil temps to warm up,this is vital mate,the tempsl MUST reach 30c before you can really open her up.Keep checking and wait for them to do so.
This will mean a small wait for the temps to come up to this heat,at about 25c the engine will catch and sound different this is the key,and at 30c you're be ready to open her up and get going.
I would wager this is you're problem
