Overheating car even with coolant and radiator full

Hello,

My car overheated and stopped on me the other week while I was driving down the road. Any light tap on my gas makes the rpm jump past 2 and 3, I wouldn't even be driving 20 miles per hour and it would jump up to 3. There are no engine lights on, no oil light, nothing. On the monitor it went all the way above the red and once the car stopped on me and all of the white smoke cleared I lift the hood and seen that my air intake or air filter came off. I'm originally supposed to have the flat filter but the person before me changed it to the cylinder one for high performance, but it slips off. So I know that's a factor. There's also a smell almost like gas it's pretty faint I'm not sure why that's happening but when I got my smog done there were some minor exhaust leaks. Could I keep the type of filter that's on there? Just replace it and I'm not sure if I have a head gasket leak but I would like to use Blue Devil the sealant just in case, would that be a good idea? I don't think it's my fans although it probably wouldn't hurt to change them but my air conditioner worked fine, I had to turn it on once my car started heating up and it cooled the car down a little.