I have an '05 dodge neon, with a rebuilt '03 motor. It cranks fine and runs great on the highway. The problem is: after it's warm if it idles for more than 4 seconds it starts bogging down and doesn't want to go. I have to stop it, turn it off, then crank it back up and take off immediately or hold the break and gas if I'm at a redlight. Not knocking or really sputtering. But when it bogs down I can push the gas to the floor ( I haven't put it all the way to the floor, just an example) & it won't get over 15 mph. It's started using more gas since this is going on. What should I check? Or try replacing first? I know it needs a new battery but i dont see that causing this problem, seems like a fuel problem to me. Can anyone help?

 

If the battery is dead, it won't run well. If you know it has a bad battery, fix the known issue first.