My 1990 toyota camry stalls at times, especially on hot days

My car has been at the mechanic seven times for the same problem and is still not fixed. The problem is hard to detect because it only stalls ever so often, and usually only after I drive it for 4-5 miles. It did this mostly in the summer, but even now it is unpredictable and annoying. My mechanic tried to find the problem and here is what he did so far; removed and installed valve cover casket, replaced ported vacuum switch, removed circuit opening relay, something about electronic fuel injection relay, did BG induction system cleaner kit and perform BG induction service. You may think that he is no good, not having identified the problem, but he has been a wonderful mechanic over the years. Please help me getting this fixed.

I’m glad that your mechanic has served you well, but s/he sounds confused. It is good to know what has been replaced or done, but do you know why any of it was done? In other words, fixing a problem should start with a careful diagnosis of its cause. It actually sounds like you mechanic is chasing guesses.

Of course, it is very hard to diagnose intermittent problems, and they never seem to want to be problems if there is a mechanic around…

Since it seems like it might be a hot weather problem, I would first be wondering about ignition components. Has anything been done to evaluate the overall condition of the ignition system? (Spark plugs, wires, distributor, coil…) When is the last time you had a basic tune up?

You are right. He was not able to diagnose the problem for certain. It was difficult I guess, because often it would not die when we needed it to. The same mechanic told us that it did not need a tune up. We bought it used two years ago and it never had one.