Car hesitation at acceloration then jumps to normal when pedal full throttle.

Hello, it does sound like an air / fuel mixture concern. If you have too much fuel or not enough fuel for the provided air -- or too much air / not enough air for the provided fuel -- performance issues like this can happen until you open things wide up to allow full on air and fuel. Additionally, emissions related concerns like EGR system concerns can cause some hesitation issues. Diagnostic testing, hands on, is needed to find out what is lacking and what needs to be done to resolve it.

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