VX Equipe wagon not performing like she used to

[ScoHar]

I have a 2002 VX Equipe wagon as my work car, it has 147,000kms on it had it since new, now im the 2nd driver of this car I got it when it had 100,000kms on it which evidently is also when my boss upgrades cars (100,000kms or 2-3 Years) well I ended up with this car as he kept it instead of trading, he just bought a couple new SS-V Wagons instead.

It has been going really well for the last 46,000kms, just recently it has been lacking in performance i.e taking a few secs to pick up when accelerating, the gears don't seem to wanna change as its about 1000rpm-1500rpm difference from when it starts to change until it actually changes, and also noticed its running rough, it isn't missing but ran about as quiet and smooth as a VN 6.

Now the next thing I have noticed is i seem to be getting 100kms more to a tank than I used to.

I have been down all the typical tracks checking leads and plugs for arcing, checked all fluids (auto is about 1/3 the way up the dipstick only ever been serviced by holden???) even disconnected the battery and cleaned the maf and T/B but still no improvement.

Just wanting to hear if anyone else has had this problem before and been able to fix it, or am i starting to get the feeling of an old car?

Now since it still runs my boss isnt going to fork out any money as im not a rep just use the car for my own stuff.

[ScoHar]

no one got any ideas?