My car has been randomly going dead when I am stopped at a stop sign or red light, it seems to do it more when the car is warmed up, and it seems like it might do it more when the a/c is on. It will idle at about 500 rpms and kind of surge and when I take my foot off the brake and start to press the gas the car will go dead, but it will start right back up. I have changed the oil, changed a bad spark plug coil pack, cleaned the trottle body, put a new gas filter on, new spark plugs, and a new o2 sensor. I really dont know what else to do and any ideas would be greatly appreciated.

 

check for a dead cylinder
Disconnect and reconnect the coils one ata time while the car is running and make note of which one DOESN'T change the cars idle.
my money is on an injector(s)
I had 3 dead when I got mine

 

Do you think the problem could be caused by a bad knock sensor?

 

i dont think it has anything to do with the knock sensor

could also be MAF related

 

No. that would just cause the timing to retard i'm pretty sure.
Beside injectors are easier/cheaper to do.

 

what is a maf sensor, where is it located, how hard is it to change, and how much do they cost.

 

I checked the cylinders and all of them are fine. How can you test the injectors to see if their bad?