engine surge/hesitation while accelerating/decelerating with AC On.

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i have honda city(Pakistan's equivalence of FIT Aria)2005 with 8spark plug iDsi Engine. it has manual transmission. old engine has been swapped with new. so engine is totally fine. problem i am about to mention remained there with old as well as new engine.means its not related to engine's wear and tear. problem of jerking/ surge/ hesitation occurs when i turn AC on and accelerate in 1st and 2nd gear, at around 2200rpms engine surge/ hesitation is felt. same goes with decelerating. it decelerates with a sudden jerk in 1st and 2nd gears. MAP, IAC and TPS sensors are fine. problem only occurs when AC is on. turning off the AC makes the ride very smooth. initially car was doing 14kms/liter with AC on but after this surging effect, car is doing 12kms/liter with AC on. fuel pump, fuel filter and air filter are in good health. as problem only occurs when AC switch is on therefore ignition coil packs can be assumed in good condition or ride would have stumbled when AC off. AC cooling works perfect and no bearing noise in AC compressor. while idling in AC on, engine runs smooth and rpms remains consistent at 900. Exhaust tip was having fuel like smell that went when TPS was calibrated. problem of surging is also decreased but still persists. TPS is now set to .53volts at CT and 4.63 Volts at WOT which made the exhaust tip smell less. initially it was .4volts at CT and 4.5volts at WOT. no engine light error code. what else can be the root cause that only initiates the problem with AC?