You need to take it to a real mechanic that knows what they are doing. The throttle body would be the last thing to replace. The IAC would be an option. Throttle position sensor would be another option. If it runs OK at WOT, I would guess that it is not the throttle body. My son replaced the tranny for a friend. After they got done, the vehicle would not idle at all. I told him to tell his friend that I would fix it for $100 per hour. He agreed. I told him to pop the hood and start it. By the time I opened the hood it was obvious what the problem was. I removed the air cleaner and re-connected one of the wired going to the TBI. I guess I need to raise my rates. I only made $0.62 for my 22 seconds of work. They opted to put the air filter back together to save $0.30.

Given the symptoms you describe, I'd definitely have the IAC valve either cleaned or replaced before spending the extra money to replace the entire throttle body.

In some cars the IAC valve is easy to remove and when it is, I'd say just take it off yourself, get a can of carb spray cleaner and an old toothbrush and try cleaning it out instead of replacing it. However, on your particular engine the IAC valve is a pain to access (it's tucked up under the intake manifold if I remember correctly). Unless you or someone you know is handy with tools and pulling parts out of tight locations or wants to remove the entire manifold and everything else that entails to get the IAC valve out to clean, I'd just pay to let the shop do it.

You should ask a mechanic for their opinion because some guesses on Yahoo might not be accurate

You have guessed incorrectly so many times and wasted a lot of money that I am dumbfounded that you are asking for more guesses! If you had taken this car to a mechanic in the first place the car would have been repaired already and a lower cost and with a warranty! Please do so now. Forget about codes. Mechanics know what to do.

I have a 1997 Nissan Altima and it's been running rough lately and I have taken it to multiple places to get scanned because my check engine light is on but no codes are showing up. I have had the EGR valve replaced, my knock sensor replaced, my fuel filter replaced, coolant temp sensor replaced, and nothing seems to help my car. Here is my problem: when my car is idleing it goes from 1 rpm down and tries to or does stall out, this is when I'm at a stop light, in my driveway. When driving it it shifts rough. It has a hard time starting even after being ran for awhile, or when it's been shut off. It just cranks and cranks and finally when I press the gas several times it starts. I can't figure out why it's doing this. I took it to a mechanic and he said that it could be my throttle body, or iac valve but he's leaning more toward throttle body. I don't want to pay for the part if that's not my problem. I need help! He said my fuel pump is good, my spark plugs look like there not receiving gas. Please someone help so I can get the problem resolved instead of fixing things that aren't my problem.