katkiller... play with sir colin and jst jump and flip on the flat ground while racing. Once you get upto L5 boost you will easily get 7-10 seconds air time for a decent jump.
Who did you use for the 10 second wheelie?
If you get past the first 5 or 10 waves then chances are you will go through the whole level. The set up at the start is the most important part then it gets easy.
I agre with tsugaroo. The AI follows a set path and enialates your plane. The best way to win is to use Nitro twice at the start and then stay in front of the computer.
Giga. I don't know why it deleted your save file but if its lagging it could be your computer. The game all loads from the internet at the first loading screen. My internet regularly drops out but i keep playing through it. If it's lagging you might need/need a new graphics card.