I've basically fixed my rough engine/idle changing problems.

I am however still getting the exhaust problems.

I just done an ECU self diagnostics test with engine on and off and no errors were reported.

the engine used almost 1/4 of a tank over a 25km run.

The exhaust is rough and smells a lot (not exactly like fuel).

So far I have checked leads, distributer cap, rocker gear, timing chain.

I also checked the TFI module and cleaned it out which fixed the rough engine and changing idle.

But the exhaust and fuel problem is still there.

What could be causing it?

There is no smoke, only white while it's cold

Was your car parked flat before you left?

Yes.

Been in the garage.

There's no stains on the driveway form leaking fuel and also the fuels been in there for 3 weeks.

It's premium unleaded (we been running unleaded for around a year until now).

Also it only does it after trips so I doubt it's leaking while it's off.

Replace the oxygen sensor. Also wouldnt hurt to replace the IAT (intake air temp) sensor.