Issues After Changing Spark Plugs

[Getphazed]

Aight as title sais i changed the spark plugs in my 1991 turbo supra. Also cleaned the k&n air filter. Now the car after a little bit of running the idle just hits 500 and drops and goes back up then eventually the car dies. Can restart it with no issues at all. Im not sure if something happend while i was changing the spark plugs but it didnt start till after i did this. The engine i know has more problems there was poil on the plugs litle on some and alot on 2. Im goin to check alot of things on it today make sure there arent any disconnected hoses, reset the computer, check to see if my intake filter is mesed up, make sure i didnt mess up the throttle cables or anything. Also i notice a vaccume sound when the car is running and when i shut it off there is like a vaccume sound and then a kinda hiss sound. Not sure if any of this helps but if anyone has any ideas please let me know.