micra k11 cold start problems

I have micra k11 1.0 16v and I have problems on cold start. the car have LPG. its easyer to start on lpg but then turn to petrol. When I start on petrol until the car have 30C degress not taking accelarator pedal properly its seems like having lot of petrol in injector or less petrol. I change the coolant temperature sensor still the same. I disconect the coolant sensor and wire a potentiometer and set on 9000 ohm the car take the gas pedal properly and starting ok. ambient temperature is about 5 degrees celsius and the coolant temperature reeds corect but the car wants 9000 ohm :) ANT Ideas