Kenmore gas range (665.75842005) Would not stay lit during preheat cycle. Replaced microprocessor. Worked for a few weeks but now starting to act up again. This time it isn't staying lit during the bake cycle. When it tries to relight (like before) it clicks four times but does not ignite.

If the oven is gas, it can only be worked on by a registered gas technician.

Faulty thermostat or gas valve regulator.

https://www.google.com/search?q=kenmore+gas+range+repair+near+me

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There are several potential causes for a gas range being slow to preheat. Here are some troubleshooting steps you can try:

1. Check the igniter: While the igniter may be coming on, it may not be getting hot enough to ignite the gas. Make sure the igniter is clean and free from any debris or corrosion. If it is dirty, gently clean it with a soft cloth. If the igniter is damaged or not getting hot enough, it may need to be replaced.
2. Check the gas supply: Make sure that the gas supply is turned on and that the gas pressure is sufficient. If the gas pressure is too low, the oven may take longer to preheat.
3. Check the oven temperature sensor: A faulty temperature sensor can cause the oven to take longer to preheat. Use a multimeter to test the sensor for continuity. If it is not working properly, it may need to be replaced.
4. Check the oven door seal: A faulty oven door seal can cause heat to escape, making it difficult for the oven to reach the desired temperature. Inspect the seal for any cracks or gaps, and replace it if necessary.
5. Check the oven igniter safety valve: The igniter safety valve is responsible for regulating the flow of gas to the oven. If it is faulty, it may be restricting the flow of gas, causing the oven to take longer to preheat.

If you are uncomfortable performing any of these troubleshooting steps yourself, it is best to contact a qualified appliance repair technician for assistance.

Generally oven burners are at maximum (preheat) until the thermostat temperature is reached and the thermostat begins to control the gas flow.
As that isn't happening it would suggest the thermostat is either faulty or incorrectly fitted, though I must admit I am unfamiliar with ovens that either have or need a control board - I have found few domestic appliances actually benefit from the inclusion of electronics.

The gas regulator is faulty and will need to be replaced. Here is the part you need to order.

I would be interested to know just how long it is that the oven does stay lit. All ovens, gas and electric, cycle off and on throughout a baking cycle, to maintain the proper temp. If the flames or the power to the element were to stay on at full power for the life of the food's required time in the oven it would most likely wind up charred. The temp would simply continue to rise, up and up and up. If that's what it appears to be doing, then it's just working normally. If it goes out completely and stays off, doesn't come back on in a few minutes, then it may be in a keep warm mode. Many ranges have a TIMED BAKE cycle available, so you can set the clock to start the oven at such and such a time, cook the food and then shut off. Once it's finished with the cooking cycle, it goes into a keep warm mode, where it will come on for a short time and then go off, to maintain about 180 degrees. Not hot enough to really cook anything anymore, but hot enough to keep it warm for you when you get ready to eat.
If this seems to be the way it's acting, then look for the timed bake function on the console and set things back to a manual mode.

How do I correct the E1 Error on kenmore Gas Range Model # 665

The glow plug underneath the over floor need to be replaced

You need to replace the temp. sensor. It's not reading correctly. These occasionally go when you use the self clean as the range gets up as high as 900 degrees. Replace it and it will solve the problem

Yup...I believe this may have been an issue with some GE models. I seem to remember a problem where some models had problems staying lit after preheating. The fix was replacing the oven thermostat. Now...the normal cycle for an oven lighting is just what you described. The glow igniter will glow first, followed by the gas valve opening, followed by ignition. Once the oven reaches optimum temperature it is normal for the gas to shut off and come back on to maintain oven temperature. However, if this is going on in a frequent fashion with the oven never getting warm, your guess is probably a correct one. Good luck to you.

probaby just the bulb holder