If i preheat my oven at 400 it only reaches about 375 then it goes down to 325 while im cooking (i put an oven thermometer in it to check it) what is wrong?

This Conversion table is from the old Gas Mark scale
I'm thinking it should be right or at least pretty close.
You could also get a cheap ($5-7) oven thermometer from local grocery store.
Put it inside oven to check actual temp achieved.

Gas mark Fahrenheit Celsius
1⁄4 225° 107°
1⁄2 250° 121°
1 275° 135°
2 300° 149°
3 325° 163°
4 350° 177°
5 375° 191°
6 400° 204°
7 425° 218°
8 450° 232°
9 475° 246°

what is your oven if is gas or electric, if is gas easy to preheat by using lower heating element, if electric? that your unit have convection? or not? coz some probelm of the oven is, 1 if the oven is no convection or your oven is single heating in upper element,if your oven have a timer and cut off in 15minute? dont use timer,use a manual timer by it your self,if you want to reach the degrees that you want check your oven if der a lower and upper heating element with convection function,that the one is the most easy way to reach the degree that you want to reach.

If you are monitoring the oven temperature with an analog style thermometer you may actually be ok, but seeing the thermometers slow reaction time.
Some newer ovens actually do pre-heat beep prior to reaching temp in an effort to conserve eelectricity.
A good home test is to try your oven at several different temps to see if there is any variation in internal temperature. Try it one day on 300, the next at 375 and another day at 450. Give your analog style thermometer time to catch up (usually just about 15 min) and leave it on for a half an hour to see if the temp maintains.
Also Beware of aluminum foil AND THE NEW OVEN LINER MATS as they can alter oven performance bay absorbing and blocking the ovens natural heat radiation and convection air flow currents that happen in all ovens, not just convection models.
Another interesting fact is that older ovens used a thermostat in them that operated much like your thermometer and was very slow to react making the oven typically about 100 degrees hotter than where the customer set it. This was just a fact of life before the advent of electronic temperature management and became noticeable when people began trying to bake older "hand me down" recipes in the newer ovens with less than stellar results.
You can mimic the older oven performance by preheating the oven about a hundred degrees higher than called for and after it reaches temp, re-set it to the correct temperature and put the items in right away.
If you find your temperatures fluctuating ask your servicer to replace first the temp sensor and as a last resort the control board as this part is usually pretty expensive.
Good Luck with this!

Hi,
Check out this tip that I wrote about this problem...

http://www.fixya.com/support/r4511800-oven_problems_electric_oven_heating

heatman101

Hello- The background panel is screened with gradients, but is expensive and hard to find. The easiest solution is to purchase an oven thermometer and allow to set for about 20 min at an indicated 350deg. Make sure that dial knob is tight and mark with a line at that point. Use a fine point sharpy, and clean surface before marking. Turn off, let cool, and turn to the new 350 mark and see if temp comes up and matches 350deg on thermometer. If it works ok, try marking 325, 375, 400, etc. ---Yes,  Clockwise is up in temp. Let me know if this info helps.   Have more if needed-  Thanks - Ed

I found the answer by checking the Kitchenaid website to find the manual. My model is KEMS308sss04, this is found on the right door frame. Website is: http://shop.kitchenaid.com/assets/pdfs/literature/Use%20and%20Care%20Guide%20-%20W10162223.pdf
You can preheat oven, but then turn off to set thermometer. Put probe in food. Put food in oven and plug in probe. The digital light asks for the temperature you want, type it in. Then the cooking method. I used convection bake at 325. Hit START. (The first time I didn't stop the oven and it didn't work. After stopping everything and starting with the probe before turning on the oven, it worked perfectly. Good Luck.

http://www.appliancepartspros.com/partsearch/model.aspx?model_id=5153992&diagram_id=1251523#d1251523
your looking for part number 67 on that part breakdown
it is the bake element and if you inspect it im sure you will find it cooked or broken
befor you actually order the part take the unit out
unplug it
and inspect your wire connections to both sides of the element

hummmm this sounds similar to what is happening to me. I am praying someone will have a solution, I don't want to have to explain to my daughter who is going to be 4 tomorrow, why I can't bake her cake.

I have just checked the baking guide in the manual and have found that it may not be us after all. (Maybe this is why they telll us to read the whole manual. Well, I never have) According to the cooking time for Baking, the range is very extensive. For example, an angel cake at 350 could take from 28-50 minutes, buscuits at 375-400 could take 8-16 minutes, layer cakes at 350-375 could take 25-40 minutes, pound cakes at 325-350 could take 45-70 minutes and fresh pies at 400-450 could take 35-60 minutes. Basically, the baking directions on the box means absolutely nothing to use Amana oven owners. We have no choice but to cook our food or baked goods until they are cooked, whenever that may be. :) Linda