no power after 80ks

[rum runner]

just a few things to list
1) i was sitting on 90 ks (in a vx commodore) behind a caravan (overtaken) the van then got to 110ks no prob at all slowed down to 80ks for a van i looked at my dash and relised that engine light was on so i overtaken the van it struggled from 80 to 110 seems no power at all grrr

2) when i put it on cruise control on it seems to use more petrol then without putting it on im talking 1/4 of a tank difference?

3) air bag light on (all the time) and it chimes when starting

[VK SL 3800]

Take it to a dealer and get the codes checked out and cleared/fixed, then problem solved.