My tercel runs fine when it's cold. When it heats up it stalls and will only start with great difficulty. We've tinkered with everything and think it's probably electrical. It stalls less when the head lights are off. Any suggestions? (IMG:style_emoticons/default/460.gif)

Yes, I believe it's your fuel pump.

These are classic symptoms. Except for the headlights. It could be your pump has less power when you lights are on...although your alternator has ample juice to power everything. Maybe it's your imagination.

Go with fuel pump. Drop your tank (empty it first). It's not that hard to do. If you go on-line, you may be able to find the pump for $50....otherwise the entire assembly will run you around $300. (And don't go to Toyota. Get an aftermarket one).

If it's not the fuel pump, the information in the post below may help.
Good Luck, Gregg