I think I need to replace the timing belt on my car, 146000 km, 2.2L
engine.

Replaced spark plugs, wires, fuel filter etc recently, bought a timing
belt replacement but didnt try because it looks intimidating.

The engine runs great, clutch plate is new and everything is smooth
and responsive, but a tap on the throttle takes an annoying fraction
of a second before the engine races. That delay is obvious when slowly
accelerating on the first gear, the throttle jumps the car forward,
stops, jumps again etc. Doesnt happen when I floor the throttle pedal,
and nor on highway at higher gears. I feel its the timing belt.

Bought the car from someone else, and dont know if the belt was ever
replaced, but the milage was 40,000 or so, and I've put a 100,000 on
it.

I opened the plastic top and the belt looks brand new. I inspected the
space between the teeth, teeth surfaces and wear, cant tell it apart
from the new one I bought. Do I still need to replace it?

Secondly, at idle, the falling side of the belt on the pulley seems to
vibrate, upto 1/2" or more. Is that normal or does it need tightening?
I tried to slip the belt on the gear sideways and it wouldnt budge,
sure seems tight.

The support right next to this gear, seems like the engine mount on
the right side of the car. Is this the only mount on the right side,
will the engine fall if I unscrew it?

While I was figuring this out, an occasional visible smoke comes out
from the back of the head, just a puff, and then nothing. Into the air
housing, the engine spits out oil, and the smaller cube air filter in
there was soggy with oil. My mechanic friends suspect either the head
gasket, or a slightly broken valve, or both. Any idea why the engine
would spit oil from the head to the air housing? I bought a haynes
booklet on the maintenance, but its very unclear on how the engine
runs, and theres no mention on how to say replace a valve.

Help on any of the above questions will be appreciated, especially on
how to replace the timing belt...