aau please help

i have an l reg coupe with the 1.0 aau engine

the revs are funny intermittently if I'm going down a smal hill in gear not touching the accelerator the car will slowly accelerate a little then drop off

sometimes i will the start the car and it will idle correctly but if i rev it its like the revs stick on a little bit and it will drop down after say 10-15 seconds

also sometimes when i start the car it will idle correctly if i gently touch the accelerator it will accelerate but if i floor it it will splutter and die i have to let go of the accelerator

if someone can help me would be a great help or point me in the right direction is it fuel sumthing sticking owt u can think of thanks dan