Brief Answer:
Information
Detailed Answer:
Hello and welcome,
You are definitely at the upper limit of safety if you weigh 180 lbs and have no history of liver disease as what you took adds up to 4000 mg. It's recommended not to exceed 3000 mg in 24 hours, but in general, for most people, 4000 mg can be ok.
If you are not elderly (I don't know your age) and have no history of liver disease or elevated liver enzymes, then you will likely be ok if you take nor further acetaminophen in any form (including cold medicines, etc) AND absolutely no alcohol in any form.
However, if you want to play it safe, you can go in to the ER where they can measure your liver enzymes (but a rise in these is usually delayed - doesn't happen immediately), and if they think you need treatment, will give you something called mucomyst - a drug that protects the liver. Mucomyst is N-acetylcholine which is sold over the counter but taken orally may not really get where it needs to because it is broken down before it enters the blood. The mucomyst they give in the ER or hospital is given IV.
So - if you took 4 instead of 2, you are right on the edge of what is safe, and so if you are pretty sure that you took 4, and if you have any history of recent alcohol use, or liver enzyme elevations, then I would recommend going in.