I have a 2003 lancer es, 170k , recently the service engine light came on, when driving If I take my foot off the gas to slow down, the rpms stay at 1500 and the car will go 25-30 by itself, but if I put my foot under the pedal and lift out, the Rpms go down to normal, if I dont pull out then the rpms will stay high, I was trying to get on highway up to speed and put the pedal to the floor and rpms didn't go up, car didnt accelerate. TPS or throttle cable problem? Open to other opinions as well just want this problem gone.

 

Could be a throttle issue. Is it drive by wire or old cable style? What was the code for the CEL that came up?