Broblem with Alfa

Hello forum user. I have one: Alfa 156 2,0 JTS 166 PS What happens to me is that when I start the car cold, the engine turns to 1200 / min. If it is warm, it goes down to 1000. What I also notice is that when I switch in empty run, the speedometer drops down to 1200 fluidly and from there it goes rather so bumpy or stocking to 1000 revolutions / min. If the speed, when starting, falls below 1000 so the motor jerks. So I have to at least Is it not normal, however, that he should have 900 or 800 turns/min. in the empty run? My father drives a diesel 2.4 jtd but the motor only jerks if he really falls below 900 / 800 turns /min. otherwise not. So I am also used to it with every car. I drove out the Alfa once and at 7000 turns / min. he had exactly 230 lt. tacho, is this also in order, because I read here sometimes, that the with 1.8 liters 230 – 240 km/h sch otherwise it’s going perfectly, what can this Macke be about? Did you read anything about an LMM and the throttle flap that you should clean it? Fals that’s true, has jmd. a guide for this, with pictures, if possible? Thank you in advance greeting Sonics