You have an older oven, and it is not self cleaning. You hate getting all the chemicals to clean with, they reek and cause a nasty mess that is hard to clean up after.
You can try a simpler route by cleaning it once a month with out all the chemicals. Turn your oven on to warm up. Turn off the oven once it is warm and place a bowl with about a cup of ammonia in the center of the oven.
Close the door and let it sit overnight. In the morning, grab a rag and a large pan of clean water and wipe out the interior of the oven. All the baked on goop should come out fairly easily.