engine surges on my north star engine 4.6 from time to time i will get a code 122 when im driving then when i turn off the car the idle goes back to normal and the code 122 will say histroy i changed the throttle position sensor and still having the same problem please help me any body its driving me nuts the car drives beautiful

 

The idle air control (think that is correct name)may be having problems. They can be cleaned but a new one is like $20. might be worht a look.