2.
Check leakage of vacuum.
When air-fuel mixture is lean due to leakage of vacuum, PCM closes throttle(ETC). Finally MAFS decreased by decreasing intake air and engine hesitation could occur.
Engine "ON" and allow the engine to warm up to normal operating temperature.
Check leakage of vacuum.
Is there any leakage from vacuum hose?
YES
Repair leakage at vacuum hose or replace it.
NO
Vacuum hose is OK.
