Engine vibration when A/C is on

I have a Toyota IQ 2010 model. I bought this car second hand having driven 50,000 KM.

When I bought the car it had power and acceleration issues, it wouldn’t even climb a small ramp. Other problems were that the car would vibrate a lot when the A/C was on but only in traffic. It used to get better when I put the car in neutral gear. Then after driving it for a year (because I had no time to see a mechanic) I took it to the mechanic.

I found out that the ABS motor is faulty and needs to be changed and it also has no catalytic converter as it has been removed. They also told me the gasket has been replaced due to overheating in the past and it’s not the original gasket used for 1KR 3 cylinder engine. So I changed the gasket, installed new piston rings, changed the transmission fluid, changed the spark plugs and literally all the filters, but I didn’t install a catalytic converter or replace the ABS braking motor

The power issue is solved now, it can climb ramps and is much better than before. So the only issue that is left is that the car vibrates when A/C is on when the car is on idle. I also made a hole in the butterfly for this issue but it didn’t resolve it. I noticed the RPM of the car is not stable, it is dropping and rising on idle. Also, when the A/C is on and I am continuing to drive there is no acceleration. When I switch the A/C off the car accelerates.

Can some one tell me what more I can do. If I install the catalytic converter and ABS motor will it become OK?