So I had put gas in the car and did some errands then later on in the day decided to go out to eat, after leaving the restaurant I drove off, went to go speed up a bit then out of nowhere the gas pedal started resisting and the engine light popped up. I then proceeded to pull over and turned the car off, a few minutes later I tried to start the car and it'd try to turn on but it couldnt.

My battery is still really good so it isn't that, I had all my fluids checked the night before and they were all good, added a little oil to be on the safe side. I've tried adding more gas to the car, jumping the car and nothings working!

Any idea what the problem could be and if its costly? I've got a 2002 Ford Focus...
Last time I tried it was a few hours ago... and I had been stranded for 4 hours trying it each hour. I haven't got the car with me but Im going to try again tomorrow, I just need to know what to look for..
Well, the engine has been replaced before and theres all new hoses in the car aswell. Theres another major part under the hood that was replaced not too long ago but I can't remember what the previous owner said it was. Could it just be I ran the air conditioner when the car isnt used to that?