Dandy. The fix is going to be real involved so I hope you're sitting down.
Go out and drive it at highway speed with the engine warmed up, then coast for at least seven seconds without touching the pedals.
When the battery is disconnected or run dead, the Engine Computer loses its memory. When started the next time, fuel trim tables will start to be rebuilt without you even knowing it's taking place, but it also has to relearn "minimum throttle" before it will know when it has to be in control of idle speed. Until that takes place, the engine can be hard to start unless you hold the accelerator pedal down 1/4", you won't get the nice idle flare-up to 1500 rpm at startup, and it will tend to stall at stop signs, (or when the high load of turning the power steering loads the engine down).
Prolonged coasting meets all the conditions, (high vacuum, time, and steady throttle position sensor voltage), the computer needs to see to determine your foot is off the accelerator pedal. At that point it takes a voltage reading from the throttle position sensor. From then on, anytime it sees that same voltage, it will know it is in charge of idle speed.
Tuesday, December 29th, 2015 AT 6:08 PM