I've been having a problem recently with my 91 Camry (160000 mi/AT). It tends to like to stall when stopped at traffic lights/stop signs for more than a couple of seconds. It will start right back up again without a problem, and I can keep on going.

-It is worse when the car is slanted uphill, but has happened on flat ground.
-It seems to be worse during hot weather, although temperatures seem fine.
-The A/C being on significantly increases the chance that it will happen, but it has happened with it off.
-Happens intermittently, maybe 5% of the time

The car was recently put into a ~60% city-driving situation from a ~90% highway, so the issue may have been there for several years without anyone noticing. I can go hundreds of miles straight on the highway without a problem, but city driving is more challenging.

Any ideas? Thanks for any and all help!

 

If the engine runs OK otherwise the Air Idle Control valve (IAC) may need cleaning. The valve controls idle speed.

When the AC compressor kicks on the engine idle should increase to compensate for the load (same with using the power steering). Is the ldle staying constant when either of these are used?

A Google search on cleaning the IAC valve will turn up many hits.