Q: Car shaking when driving

Fuel injector cleaner typically will not affect anything in cars as it is formulated for modern vehicles and is safe for all sensors. The issue may have started right after you added the cleaner, but my suspicion is that it was just coincidental. If you were adding the cleaner to try to repair some issue with your fuel system, it is likely that the issue got worse. Fuel injection cleaner does not repair problems in vehicles. It is a maintenance item that when used regularly can help keep injectors clean but it wont clean clogged injectors for example. I suggest seeking help from a professional mechanic to diagnose what’s causing your car to shake and assess your battery problem as well.