2003 GMC Yukon Code P0174

When cold the engine starts up and runs at to high of an idle and when you hit the throttle the engine rpm is slow to come back down. Once it has warmed up the throttle responce seems normal. But the engine feels and sounds like it going to shut off just for an instance. All most like a miss but does not feel like a miss. Also the lights will dim and back to normal along with what the engine is doing. It sets a code P0174 system too lean Bank 2. There are three lights ont the cade reader I am useing Green, Yellow and Red for the emissions system. When the engine is doing it's thing the red light is on. The alt output is 14 volts.