Hi Scotty,
I have Toyota Corolla 2009 with 98xxx km on the odometer. My car was perfect just before I started her today evening. After starting AC, suddenly the RPM started going down to around 500 and then back to normal. It occurs some times only. What should be the reason behind this issue?
Load test the battery and alternator first.
I drove my car several kms after that and suddenly problem of hesitation increased. I will try to change spark plugs and ignition coil now.
Check the IAC and TPS for function, connections and wiring and grounds.
Okay. However, 2nd piston from the left has stopped working. The car is now on 3 pistons. Could that be due to spark plug or ignition coil? Should I have to switch them with other and check first and if problem is there, should I have to change them?
Switch the bad cylinder for a known, good coil and see if it fires. If so, you have a bad coil.