I have a 91 Toyota Camry LE with 180k miles on it.  It has 6 cylinders
and is automatic transmission.   Recently, I have found that after
running the car for about 40 minutes or so, it will begin to idle
roughly at stops.  At first, I thought that perhaps it was because I
put a can of BG44K in my gas tank.   (It is a fuel system cleaner that
is very powerful).  But when I thought about it, it didn't seem to
make sense that it would cause the problem after the engine got hot.

Is it possible that something about the EGR system could cause this?
It would have to be something that changes with heat and driving.

Thanks,   Al Kondo