You have not used the proper pressure. NO food other than fruit will require 5 lb. pressure. The least you pressure can low acid foods is 10 lb. depending upon your elevation.
Where did you come up with your information ?
Botulism will only be destroyed at 240 or above.
Please, discard your improperly processed foods, as they are unsafe.
Headspace is determined by the type of food. You need to read each recipe/method carefully and follow them EXACTLY.
I suggest either the site you listed or a current Ball Blue Book.

The usual rules: Don't over fill the jars leaving a couple inches of headroom. put the lids on not tight but on use a few inches of water, vent the canner for 10 minutes before putting the weight on yadda yadda yadda.

First, those aren't "the usual rules" so I hope you are just abbreviating. ;) Otherwise there are some real concerns there. Head space is specific. Chicken stock is 1". Marinara sauce, assuming it is an approved recipe is 1/4" headspace and is normally BWB canned, not pressure canned (but may be done at 6 lb. for 20 mins. depending on altitude. So is the amount of water required in the canner. So is the lid tightening. All specific.

I've used it three times and each time I have boil over issues. I've done: Chicken stock, Marinara sauce and Vegetable stock.

It is called siphoning when talking about pressure canning, boil over in BWB canning. Siphoning has several possible causes including too much heat, too loose lids, too much heat fluctuations, improper headspace, etc. See the chart linked below.

I use the 5 pound pressure setting (New Jersey) and run it about 228 F.

Uhhhh, 5 lbs. isn't approved for any of those foods unless your "marinara sauce" is really just plain tomato sauce. And how are you determining the supposed temperature? The canner isn't telling you what the internal temperature is. There is no thermometer on it. So how do you know that At 228 I am making Steam. ??

And even if it did the temperature isn't the important factors in pressure canning, the pressure and time is and both of those factors are very specific. EX: pints of chicken stock are processed at 10-11 lbs. for 20 mins. Period.

Perhaps I am misreading your post, but from the information you have provided, there are some serious misunderstandings about how to properly pressure can foods. Could you please provide more details?

Dave

PS: is is possible that what you have is a very old AA? Second hand I mean?

Reason I ask is that you mention temperatures and a poor manual and AA has a great manual and many decades ago some canners came with a thermometer gauge on them rather than a pressure gauge. This was back in the 30's and 40's and those canners are not safe to use without the necessary upgrades like getting rid of the old gauge and replacing it with a pressure gauge, a new over-pressure plug, etc. If that is what you are using then your foods have been way under-processed and would not be considered safe to eat.

Here is a link that might be useful: Causes of siphoning

Not that Dave or Linda need my help, but I wonder too where you got your instructions for pounds of pressure or length of time to process. There shouldn't be any 'dialing in to a time or temp issue' - there really is no issue (and temperatures aren't given in canning recipes). The recipes give precise pounds of pressure for an exact number minutes, count begins after venting finished, weight placed, pressure reached, and not before.
(each gives an amount of headspace for the product too, more or less isn't an option)

I downloaded and read through the 48 pages of the current All American 921 canner manual, thinking maybe there was someplace where cooking and canning recipes could be confused (my canners are Mirro). No confusion, the only place in all pages I could see 5# mentioned at all was part of a recipe for white fruit cake, and only that one recipe.

The 921 should be a wonderful canner - Do you have a current copy of the Ball Blue Book? Illustrated and that helps, available most places canning supplies are sold.