99 crown Vic slow to accelerate ac blows warm then cold when it picks up speed

Hello, your Crown Victoria should never leak refrigerant, nor never need a charge. If it does, there is a leak that must be repaired. This would be for your air conditioning system warm / cold concern. For the slow to accelerate concern, you have some kind of engine performance problem which needs troubleshooting performed to resolve. You could have an air intake restriction, fuel delivery concern, ignition spark issue, or emissions system concern -- including even an exhaust restriction. Testing by a trained, qualified technician will get down to the root cause.