I have an issue with my car. When I start the car, it idles just fine. Hitting the gas pedal it only goes up to 5000 rpm at it jumps till there. After the engine gets warm, it jumps only till 4000 rpm. While driving, the car hesitates really strong, making it impossible to drive and eventually stalling at a stop. If I leave the car to cool down, it works a bit better. The engine is an 1.5 16v DOHC. I’ve replace the fuel pump, spark plugs, air filter. I’ve checked the ignition coils and they give me a reading in 10.5 kOhms. What could be the problem?