Car stops and starts when I press on the gas

My brakes are working fine, and the car starts up okay. However, when I press on the gas and go anywhere over 20 mph or so, my car will start, then stop, then start, then stop… Until I step off the gas.

There’s also a semi-frequent squealing noise whenever I press the gas.

The Service Engine Soon Light is on.

Any ideas as to what it is?

No idea. Can you get to an auto part store and have them read the code for the service engine light? The code # can help point to what the problem(s) might be. What year is the car? How many miles on it. What type of maintenance history? The start and stop may be a problem with plugs, wires, fuel filter. The squealing may be the serpentine belt slipping.

That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.

I took it to AutoZone (Without any problems, mysteriously) and got the following results:
Number 3 cylinder misfire
Probable Cause:
Ignition system fault, Fuel system fault, Vacuum leak affecting one cylinder, Engine mechanical condition.

Engine over temperature (overheat)

My car is a 2005 Nissan Sentra with 62710 miles on it. I’ve only ever had to take it in for standard maintenance.
I think the reason why it didn’t happen today is because I only drove a short distance- When the problem first arose I was driving home from a competition 30-40 minutes away, and the distance exacerbated the problem.

Between the engine overheat code and the cylinder 3 misfire I think one thing to worry about is a head gasket problem. Has the car overheated? (Temp gauge in the red?) Have you checked the coolant level or lost any? Pull out your oil dipstick and look at the condition of the oil. It should look something like maple syrup. If it looks more like a milkshake you may have a problem there.

I think that you just need to take it to a shop - find a reputable, local, independent shop. Not a chain operation.