My 1994 Buick Century starts and runs fine when it is cold. After it runs for a while and is warm if I stop the engine it will not re-start. It acts like it wants to flood out. If I wait until it cools off then it will start and run fine.

Think about how the vehicle is acting. Starts fine when cold, hard to start when warm. In these computer operated systems, the computer runs everything. Starts fine when cold: the computer has the engine in cold start mode putting more fuel in till it warms up. Temperature sending unit in the manifold sends a message to the computer telling it to stop the cold start mode and it stops dumping excess fuel into the cylinders and it runs fine. IF, mind you, IF the temperature sending unit is faulty, it's not telling the computer to stop the cold start mode and is flooding the engine with fuel cause it's sill in cold start mode. This is my take away on your situation and the temp sending unit is something to check to be sure it's functional. Check it out. I hope this WAS the answer to your problem my friend. It's typical. Luck to'ya Bro.

ecu bad i had tht problem

without knowing much more info about you engine and systems on board, I can give you the most likely.
If you have a triple coil direct ignition then the coil pack is the item to test. ( they fail as they warm up ) If you are describing ( flooding ) as a lack of power, this could be a fuel starving condition and no Black smoke coming from the tailpipe, So if that is the case, look at testing the fuel pressure and or fuel filter.

Those are the most common causes of failures .

Good luck .

Number of possibilities. See if you have any diagnostic codes stored. Could be throttle position sensor, coolant temp. sensor, hard to say. I would start with the codes. Does it start easy when warmed up, and run good? Boy, I just don't know.

Air filter and dirty throttle body.

a bad thermostat-testit--have car scanned for bad codes--giv it a tuneup-new plug wires and distributer cap--then throttle body and idle air cleanin--get a haynes book at parts place

check fuel pump pressure.it should be 41 to 47 psi.

You might want to check the ECT (engine coolant temperature sensor) It could be defective and telling the PCM (car's computer) that the engine coolant is cold all the time.

spark plugs known problem when cold

Have you tried replacing the pick-up coil?