Ford: throtle, coolant level, engene

Question
I have a 98 ford ranger 2.5 the engene will stay at a high rpm when foot let of pedle I have replaced the mas air senser did not help any ideas?

Answer
brian need you to  ck a few things coolant temp sensor readings you need a volt meter or a scanner,coolant level,look inside the throttle body to see if it is dirty or full of oil if so clean it with throttle body cleaner only,and IAC control valve.the best thing to do if you don't have a scaner just go to auto zone and have them scam it .It's free.let  me know if there are any codes and what they are.