320d hunting when idle and during rev range

wow no year car stated nor a country x10 worse.
welcome to our USA forum!
the country with ZERO, carry cars. not a one. here
and due to that , no books here nor coverage at mitchells. either.
That is a G13 engine, (not m13) is my 1st guess.
Most Suzuki's with tiny engine and run a map sensors, not MAF
so is called SPeed Density system.

if yes, the that means ALL vacuum leaks cause fast idle.,
armed with that juicy fact, we know why it races.
you never said and actual RPM so no Tachometer?
only 2 causes. a huge vacuum leak
or unlikely the ISC stuck wide open with gunk inside, (clean it?)
ISC is idle speed control.
old suzuki's had man killler ISC software, my 91 did it.
and all others like it........
it would hunt idle like mad with any vacuum leak.(of any kind)
today this is very *******, this mode. (hunt)
toyata cost them $1billion in fines for this same deal.

but Clutch drivers have no problems with idle hunt, "skills"
what year/country.?
please showa photo of engine. ?
and win. a win/win
you win and I win not guessing all that.

fact 2 , is that that hunt tells me the ISC is moving fast.
so is not stuck. (99% says R3PO)
unplug ISC see the hunt end? sure.
the ECU has lost its wits. from..... this....
it sees a massive air leak (vacuum map readings ) and then (dumbblly ) hunts it like mad, (bad Firmware code) but real.
i can demo this is seconds hood up.
causes?
1: vacuum hose fell off.
2: same hose cracked.
3: brake booster diaphragm cracked, sucking air big time)
4: lots more,. even gunk under throttle plate blocking it open.
and more. lots more. can cause lots of vacuum leaks.

perhaps some water condensation in the empty tank that then caused the smoke and shaking during warming up.

Refill with good branded Diesel a full tank and have a drive for 30 mins possibly warming at high revs (or low gear to warm faster)
Enjoy

Check your igniting system,, and your fuel system

seems like theres a build up of carbon in the intake. you can try the pour in gas tank cleaners for fuel injection cars which you have and after 2 or 3 of those with 2 or 3 full tanks it will clean the injectors and the carbon out of the intake. And if you really want to get them cleaned up even better and stop all the rough idling, take the intake off yourself and clean all the black stuff off anywhere you see it. Thats the carbon build up. Especially on the butterfly valve area. It will not only run better for you but get better gas mileage as well.

CHECK THE TEMPERATURE AND OXYGEN SENSOR

I had a similar issue while driving the car at about 70 - 90km/h. I also had horrendous vibrations. It ended up being the original trans fluid requiring changing to a more superior product than what they originally came out with. The car had done less than 50000km.

bad CKP sensor CMP sensor out of timing go to auto zone have them run a scan

The fast idle valve is inside the throttle body. Sometimes it backs out and needs turned back in (it's threaded). This will cause the loping idle.

Get transmission filter changed with new fluid. Honda does not recommend transmission flushing.

engine lite on? would ck to make sure there is plenty of coolant in system. low coolant may cause idle hunting. also could have a vacuum leak or air intake restriction. ck air filter

It could have any number of problems first check fuel pressure, and then check to see if your getting proper spark from the plugs and wires. Also if there are any engine lights on get them check.