I am running it on petrol... And I recently got its carburetor cleaned and adjusted, rpm adjusted, air filter, petrol filter and I think there was some third filter as well changed (installed brand new ones).... And I got its ac system completely serviced, washed, and filled it with totally new gas....!
Don't know about the spark plugs.... The AC is fine actually...... But if the car keeps on running for some time its efficiency decrease somewhat during the Day.... and the air it spits out does not feel considerably cool..... During the night I have to stop it at different intervals as it cools the car very nicely.... But during the sunny day it is not much efficient... But this is also not the main problem..... As soon as the AC is turned on, it feels like someone has put a lot of weight on the engine and the rpm drops considerably... Like suppose if it is on 3500, it goes to 2000 or less..... and so the acceleration!