I have a '97 Protege LX. About maybe two years ago, I had the air induction system cleaned which included the ISC valve and this had solved the problem I had with rough idle/stall when using the a.c. But now I'm noticing that the idle is fairly rough even without using a.c. and engine often struggles to keep the RPM at 750 (normal idle speed). Should I go ahead repalce the ISC motor or could this be another issue? I am going to change the air filter this week and this may help, but should I be looking at anything else?

 

At a 191k miles there are a lot of possibilities. What is the condition of the spark plugs and fuel filter and how long since last replace? Also consider plug wires and other wear items. Your valves should be adjustable and may also be in need of service. Does the engine feel like it is missfiring or just a low, unstable idle speed? I would not replace the IAC just because, as it is not a cheap first guess. Look into the more common items above first.

 

Hey,
I posted higher up about my airflow sensor. Part of the problem I was having was the car would struggle to stay at idle with the AC on. It would continually threaten to stall. By fixing my airflow sensor, it fixed everything. I suggest you look at that given the fact you changed your intake. Maybe that messed something up.

 

Good suggestions. That airflow sensor may be the issue, but this has been going on before I changed the air intake hose. I'm due for a tune up so I'll see how it goes after a new set of plugs and wires.