So my friend has a 1991 honda civic 4dr stock 1.5l and when it starts it has a slight shake to it. When you drive it down the road the shake slightly increases. When the car first started it was idled at 1500rpms then when warmed up decreased to 800rpms. It doesnt seem to run rough but when coming to a stop it wants to die. The check engine lite is not on. If any one has any ideas please let me know, my thoughts were o2 sensor throttle body sensor or map sensor maybe bad but if it was an o2 sensor I know for sure the check engine light would come on and it would run like shit.