empty running problems

moin moin love for friends I unfortunately have a problem my escort pacific cabrio mk7 has empty running problems in the cold zjstand drejt he at 2000 when he is going down to 1300…. if I drive and brake in the warm condition he sometimes goes to 500 turn…. so he grabs as soon as I knock the kick fully around…so he regulates but after a time up again and in the lerlaufschaft he also nciht constand a speed to keep fluctuations vopn 100 -200 turns are always there.. .. could that be on the air mass meter? or rather on the training controller and if so, where is the empty running regulator? is there a way to check that? mfg torben