I wrote this as a followup in a thread above, but decided it is useful and important enough for a new thread. Anyone with an older Camry is likely to have to deal with this sooner or later, and may spend big bucks unnecessarily.
The Problem: Here's a classic story with older Camrys. The car starts fine and may run okay for a few minutes. But then as it starts to warm up, it begins hesitating on acceleration and/or stalling at stoplights. When it is fully warmed up the behavior goes away. The problem is usually worse after a rain or in humid weather. Once it starts happening, it gets more and more severe rather quickly. This one baffles mechanics, who often wind up replacing a series of expensive parts, all to no avail. Ironically, the true fix is very easy and cheap.
The Cause: '90 Camrys (as well as several years before and several years after-I'm not sure of the exact range of years) have the coil inside the distributor-a bad idea. I don't know when they stopped doing that. When the engine starts, it exudes moisture (a product of combustion). The moisture condenses on all surfaces inside the distributor. That's okay when the car is newish, because distilled water doesn't conduct electricity. But when the car is older it has a fine film of debri coating all surfaces. When those surfaces get wet they conduct electricity and the primary coil shorts out. Then when the car fully warms up, the sufaces dry and the car runs fine again.
The Fix: Use isopropyl alcohol (rubbing alcohol) and cotton balls or Q-tips to clean all the surfaces inside the distributor. Take off the distributor cap and the black plastic shroud that covers the coil (snaps off and snaps back on). Clean everything with liberal amounts of alcohol. Don't worry if it drips all over-it drys without harm. Don't be discouraged if you don't see a lot of dirt on the cotton, were' talking trace amounts here. Give special attention to the coil wires. Also clean the inside and outside of the distributor cap while you're at it. You'll be amazed. You'll have to do this every couple of years now.
-- Fred