Toyota Rav4 gasoline, revolutions wave when taken off the gas, when braking

Hello
At the outset, please be understanding for nomenclature and lack of professionalism, thank you! :-)

Toyota Rav4, 2001, gasoline 2 liters, with LPG (about 250 thousand km)
The phenomenon is strange.
When driving around town, almost every time the gas is released in front of the headlamps to neutral (braking), the engine speed starts to wave up and down. Sometimes they drop to almost 300-400 rpm and then go up to 1500 rpm. This way it can wave 2-4 times and then calms down at very low speed.
At rest (on people / standing), the engine runs fairly evenly, does not wave, although at very low revs.
When gently adding gas to petrol, you feel like a slight delay in the reaction of accelerating the speed of the car. Time lag, as if a fraction of a second he wondered. Less on gas. When you add gas quickly (strongly to the floor), on petrol and gas, the car accelerates vigorously, having power.

(and it is similar on gas and petrol)

PS
One of the 4 candle coils died last week. Coil replaced with a new one. Candles preventively replaced all 4 for new to LPG. The air filter with pipes was removable. I suspect something might have been missed here.
In the attachment I will send a video made by phone
Please let me know where to look?

greetings
"napkin"

gromleon wrote:

Maybe the brake servo is "leaking"

?

To check for leaks in the air intake system, maybe some vacuum hose is not installed or leaking.

Hello
I guess too ... We took off the air filter with the throttle inlet pipe. Then we probably missed something ... Does anyone have a drawing or a photo of the snakes, how and where should they enter?
By the way, do these Toyota models have something like an EGR valve?

greetings
"napkin"

In that case, probably one hose has fallen, for example, at the intake manifold. Hence, there may be such symptoms and ailments.
Disassemble the filter and pipes, disconnect the flow meter first. Below them, on the side of the windshield, there is an injection rail, wires and pipes. It is worth checking if they have not fallen off, if they are whole, they can also get dirty.

Hello
I couldn't stand it, I went to check ..., unscrew the filter again, remove the pipes, shone a very strong flashlight ... Exactly!
The reason for the problems was an inconspicuous little black tube. It was lying on the black collector, between the gray-black wires, blending perfectly with the background After putting the hose in place, Toyota walks like a watch, like "newborn"
Thank you greetings
"napkin" ;)

PS
When operating on a Toyota engine, place a step under your feet to be higher! I put a small but tall Euro pallet under the car. This made it easier to work and look into this part of the engine compartment (at the pit)