About 2 weeks ago I had an issue with my 1998 Nissan 200sx. The Car (Cold or Hot) would stall when I started it. Following simple instructions from my cousin (a mechanic), he suggested to clean the Idle Air Controller using a Carb/Choke Cleaner. I did it just as he said, waited 20 min, installed it and... WOW, Car started right up, and held a good idle.

BUT (there is always a but).. . Now when I am driving, If I am above 2000rpm and let go of the accelerator, the car will drop to 1500 rpm and surge up to 2000rpm about 4 times and then stop. (during heavy traffic, it has caused me to have to hit the brakes to avoid an accident).

---So, does anyone have input? I heard that this could mean there is TOO much air getting to the Throttle Body now.



I'm not a mechanic, but a DIY'er willing to get my hands dirty. I've been doing routine and intermediate work to my OWN cars.. . An issue only when I do not have the right tool. :)
I am hoping this is something I could do myself.

. Ensure there are no vacuum leaks.

. Check for codes--the Crankshaft Position Sensor may be bad.

I recently replaced the Camshaft Position Sensor in a friend's 2006 Nissan Altima. Afterwards, it fired right up.

OK, I'll check for vacuum leaks. The check engine light hasn't come on, could there still be an error code?

There may be a "soft" code, which may tip you off before a "hard" code is thrown and the CEL comes on. Soft codes sometimes portend problems before a component really starts to fail. I suspect an ignition system problem, in your case. The IACV shouldn't have any bearing on your car dying while you are driving.

Within the last 40,000 miles, have you changed the platinum spark plugs with the same ones that came in the car?

If the Check Engine Light isn't on, a pending code may be stored but you'll need an appropriate scan tool to pull it out and read it. Many "code readers" don't have the ability to read these pending codes.
Ensure that when you reinstalled the air inlet that it is fully sealed all the way around, especially at the bottom where it's out of sight and can roll during installation.

No, I haven't changed the spark plugs in the last 40,000 miles.. . I am not certain if my engine model has the platinum sparkplugs

Regardless, then, I would change them--stick with NGKs.

Your mechanic cousin was wrong on one thing. Never use carb/choke cleaner on throttle bodys.
You need throttle intake cleaner for injected cars. The other is for carbs, Very harsh chemical, and most likely washed all those carbon deposits right down the drain so-to-speak into the IAC air inlet.

Thanks, I'll try to remember that if I need to do this again :)