I've read about a similar case that turned out it was due to some loose insulation that got into the gas input line and ended up blocking the gas flow to the oven. In this case the situation was an extreme reduction in the ability for the oven to reach and maintain temp. First, does it take lots more than 30min to reach say 350F? Crank it up to 450F or 500F and see if it ever gets there. If it takes more than an hour to get up to your baking temp, then it's possible just the act of opening it up and and putting your food in is cooling it down enough that it takes another 30 min to get it back to your baking temp. Slow preheat can be caused by restricted gas flow. Here's a trick to try that I use to use. Preheat the oven and once it's at temp and holding for 10-15min, then open the oven door for a minute or so. Close the oven door and wait for the flame to come back on. Once the oven has just reached it's set temp but the flame has not gone out yet, open the door quickly and put your food in. Most oven's overshoot the set temp a bit to keep the it from going on and off and back on too quickly. This trick might help the oven hold it's temperature right after the food goes in. Another thing to try is take two oven thermometers and put one towards the front and one towards the back. Then bring the oven to 350F and see if there's a significant difference between the readings. You can move them around the oven to look for any pockets that might not be maintaining temp. Usually, this will be near to door or one of the heat vents. One silly question is when you do your baking, you don't open the oven to check on it do you? If you do, then the obvious answer is that the oven temp is cycling up and down. If you husband has an advanced digital temp probe, it should have an min/max record. To use it, put the probe in the oven (not touching any surfaces of course) and bring the temp to some set value like 300F or 350F. Then reset the recorded min/max temps but make sure it's at temperature before resetting. Let it go for 30-60min and check the min/max (and average if avail) values. They should not vary much. Good luck and let us know if any of the suggestions worked.

I have a GE profile Gas range - the burner grates clean up easily if I put them in a large ziplock bag with ammonia for a few hours, or even overnight - however, the oven exhaust area (at the back of the stovetop) is all brown from several years of use - NOTHING has burned in the oven, this seems to be regular exhaust from roasts, meats etc. I can't find a way to get at the grime - it seems to be under the glass (between the glass and the metal of the stove surface. Does anyone have any suggestions? Thanks

I would think Siemens (which is Bosch in the US) would be a better choice than Smeg for the range. The folks on Mumsnet much prefer Siemens to Smeg. You may want to search there as well. Also, as a point of information, Smeg has begun selling ranges in the US. And furthermore, there are plenty of international people on this forum. Lastly, I think there is a problem with how people see posts here, but the OP did post in the Appliance Forum as well as Building a Home. On my screen you can see the multiple headings right above where the question is posed.

@wdccruise I remember seeing that video 6 years ago when it came out, but forgot about it until now. We mostly cook vegetarian and some fish, and from what I gather from some research from people who use this, vegetables do quite well, and more importantly, leftovers. We think it will be more useful to us than a microwave drawer or combi microwave, which are the alternative options for the space. We are not expecting it to be the end all be all, which is why we're not going with a $4K Miele. @chispa Thanks for sharing. It's good to hear that people who get combi steam ovens are enjoying them. Your model is certainly a nice one. Given that this is our foray into this appliance, it's out of the budget we set for this. I'm hoping some Fulgor Milano and Smeg owners share some feedback. It's surprising to see how few reviews of these products exist on the internet. There's also brand called Fotile that I know little about.