hi ive got an n reg mk3 astra 5door with the 1.4 8v mpi engine in trouble is i have a problem with it when the engine gets warm in traffic or summat i seem to lose power when i put my foot down but the engine just seems to suck more air in but not pick up but if i drive it till it cools down the power seems to get better and also it happens if i turn it off for a few mins its like its getting heat soak into the air filter or summat but i have a good cold air feed to it. when it cold its really nippy for a 1.4 and it only does it sometimes ive tried the lambda sensor, injectors, gettin more cold air to filter, its helped but not cured it have u any ideas it doent burn any oil either as ive just rebuilt the engine i think its a fuel problem but dont know any help would be appreciated cheers damen.