i have a 92 trooper it will not hold rpms at one spot it acl. fine and it runs fine when its first started but it starts dropping cyl.as it warms up i have changed all sencers except for ecm and i cant find one of those any ideas .its about ready to be cut up for scrap.it has 3.2 sohc auto. and can anyone tell me y the ecm is 92 only