Kenmore pro oven slow to preheat. My Kenmore pro single wall oven takes 30 - 45 minutes to pre-heat to 350.

SOURCE: Maytag Gemini electric oven

Well my friend these type ovens have eyes and sensers. It could be that you left something on the sensor when you were cleaning it. That is if it is not self cleaning. Self cleaning gets real hot and could affect your appliance in some way. It shouldn't but it might.

SOURCE: maytag gas range I'm not sure of the model #/range is nine years old

YOU OVEN IGNITER IS PROBABLY ONE STEP AWAY FROM GOING OUT.

SO REPLACE IT AND YOU SHOULD BE UP AND RUNNING.

SOURCE: slow to heat up

Most likely your ignitor is going bad. This is the part that glows before the gas comes on. It has to draw the proper amperage to allow the gas in the oven to light and burn. Some ignitors glow and look good but are not drawing enough amperage for the gas valve to open, with the problem you are describing.

Very fragile part, easy to break,
good luck.....

Testimonial: "Thanks so much. We will try to fix the problem based on your information. "

SOURCE: Maytag Prec touch 750 lower oven takes too long to preheat

This is a common problem that happens when the oven gas control valve is sticking. This can be caused by a weak hot surface igniter or a defective gas control valve. One thing that you can try(be very careful doing this) is to give the gas control valve a light tap with something hard like a wrench when the oven is turned on,igniter is glowing but the burner is not on. You will need to remove the broiler/storage drawer at the bottom of the oven. Once you pull the drawer out you should see the gas control valve at the back of the range. Try turning on the oven and lightly tapping the valve housing. This may loosen up any debris inside the control valve housing that might be causing the problem. If the oven burner comes on then try completely turning the oven on and back of several times. And when I say completely I mean turn it on after the igniter is not glowing and burner has shut off. This works about 30% of the time. If the burner control valve stick after trying this procedure then it could be the control valve and/or the hot surface igniter defective. The hot surface igniter would need to be disconnected from it's harness and tested with an OHM meter. Most igniters should have a 500 to 700 OHM reading. If you get a reading that is way off then the igniter is defective and replace it. If the igniter tests good then the gas control valve is suspect and replace it. Most appliance parts retailers will test your igniter for free. When the igniter is on it should glow very brightly. If it is dim then that is a sure sign it is bad.

SOURCE: Oven takes too long to heat up

if it has an electric oven ignitor, this may be bad not getting hot enough to ignite the gas in oven.