I noticed this right after I bought my Jeep but lately has gotten more steady. Basically, it would idle at around 900rpm which is about normal, cruise on the highway at around 2K rpm. At first it was just occasionally but now it's constant. At idle it hangs around 1500rpm and highway speeds have it around 2500rpm, it's like it's not shifting down a gear. It doesn't run bad by any means but I'm more concerned about the mpg hit from running at a higher rpm when cruising on the highway. Any pointers as to what could be the issue here?

Nick

 

IAC, Faulty TPS. Check those

 

IAC I'm guessing is idle air control? Also, how would I check if the TPS is faulty?

 

Just google how to test tps, there are many write ups on it.