2005 ford focus dies in reverse and drive idles good until shifted in r/dr or when ac is turned on?
Those two circumstances put a higher load on the engine. You may just need a throttle body cleaning. They can get sticky and not open properly causing issues. A basic cleaning you can do. I would scan for stored codes with an obd tool. Check your transmission fluid level once engine temp is up. Good Luck!
a remote starter wiring issue if applied , cause they are junk!
Search Ford Focus Questions
Ford Focus Experts