If you bought a used vehicle in MA, in as is condition, are there any time lines or conditions that would nullify sale, or is that it?

What do you think "As IS" means?

Depends on if you have some weight with the boys in NYC. They can always make them an offer they can't refuse if the dealer ripped you off.

Fraud is the only thing that can nullify an "AS IS" sale. But that can be hard to prove. Next time have any vehicle you are contemplating buying inspected at by a trusted mechanic before the purchase. Best money you will spend. 

Almost none............

Fraud might. Also if you were sold a stolen car. You would have to prove fraud in a court action that you initiate. Stolen vehicle action happens when you go to register a vehicle that was reported stolen and suddenly have to explain why you have someone's stolen car. Mass RMV might have more and better info.

Other than that, "as is" is exactly that. It is up to you to inspect the car before you pay for it. The recommended method is to have some good mechanic inspect it beforehand. Always have the seller provide you the title, which he signs over to you in front of a Notary Public. A good notary knows all the particulars of auto title transfer and will keep you or the seller from making mistakes.

If you bought your car from a dealer, you might want to check out the state's Used Vehicle Warranty Law -- https://www.mass.gov/guides/guide-to-used-vehicle-...

If you bought from an individual, you are out of luck.

SORRY,  but the law is BUYER BEWARE. You would have to prove that a seller intentionally deceived you which is all but impossible to do. As for "timelines", the time period and conditions for the return of a vehicle must be explicitly stated in the sales contract.