1. Engine misfire: A misfire occurs when one or more of the engine's cylinders don't fire properly, causing a loss of power and an uneven idle. This can be caused by several issues, such as faulty spark plugs, ignition coils, or fuel injectors.
2. Vacuum leak: A vacuum leak can occur when there's a hole or crack in the intake manifold, hoses, or other components that allow air to enter the engine unmetered. This can lean out the air-fuel mixture, causing the engine to run lean and flutter.
3. Fuel pressure problem: If the fuel pressure regulator is faulty or the fuel pump is not delivering enough fuel, the engine can run lean and cause fluttering.
4. Engine sensor issue: A faulty oxygen sensor, mass air flow sensor, or throttle position sensor can send incorrect signals to the engine's computer, which can affect the air-fuel mixture and cause fluttering.
5. Transmission issue: If the transmission fluid is low, the transmission may not engage properly, causing the engine to flutter.
6. Clogged catalytic converter: A clogged catalytic converter can restrict exhaust flow, causing the engine to flutter and lose power.
To identify the cause, it's best to have a mechanic diagnose the problem and perform the necessary repairs.
