Car wont run once warmed up

suspect low fuel pressure to the injectors
run the fault codes to determine where the fault may be before you spend money

You have an intake vacuum leak. The vacuum is sucking in water and causing the truck to run rough. It may get better when the truck is hot because this sometimes causes the plastic or gaskets to swell closing up the leak. To confirm ... when it's cold you can start the truck and spray some brake cleaner or quick start around the sides of the intake and you will see the engine will rev up a little.
Hope this helps.
Sam

It Sounds like it is staying in the "cold start" routine. It also sounds like the diagnostic computer is not working right, because it must be rich and the O2 is not telling you a thing.

I would start by looking for a temperature sensor. You may have 2, with 1 being for the dash and the other being for the engine controls. You want to replace the temperature sensor for the Engine controls. This will help get it out of "cold start" routine.

Change your thermostat. The onboard computer does not monitor operating temperature.

Fuel pressure regulator. Have pressure checked.It could be forcing too much gas in each time an injector opens.

If you can not do this yourself, tow it in. At 2 mpg it may be cheaper to tow it than to drive any distance for repair. The Mechanics are going to need some gas left over in it to work on the engine.

Also turn on ignition and energize the fuel pressure, check for leaking fuel lines. Put on fuelcap locks if fuel drops when parked.

For this much of an extreme problem, I would like to know what you find wrong with it. I hope my solutions help.

sounds like it is out of time for the running part and it could also make it run a little on the warm side

SOUNDS LIKE YOUR CATALYTIC CONVERTER IS DYING

Replace the catalytic converter and EGR valve

it may be a ignition module you can have it tested if you remove it at your local autozone for free. and check the crankshaft position sensor also

When is the last time she had a tune up?
I would start there. Plugs, Wires, Distributor Cap and Rotor. Hope this helps you and thank you for using FixYa!

Have you checked your alternator?

seem like you got the same problem as my scion xa, check the fuel pressure regulater. bad regulater some time smell like leak gas. auto zone might cause you about $80.00.