How do you fix the car running on lean?

First you need to find a root cause to a lean condition which can vary from anything like a clogged fuel filter, weak fuel pump, dirty fuel injectors or even a vacuum leak of some sort. If the problem is worse when cold a vacuum leak is a good possibility. Sometimes an intake gasket will shrink when the engine is cold and swell as the vehicle warms causing a lean condition. All of which we could test for. Tim, Dale's Service, Davenport IA 563 388 9363