Thanks for all of your advice. I found the solution and it's crazy simple.

A couple weeks back Zel was getting worse, so we made a vet appointment. He was just checked out in March and given a clean bill of health, but we wanted a second opinion. We also wanted to find a vet closer to where we live now. Then he coughed up the largest hair ball I have ever seen and calmed down a bit. I remember looking at it thinking "no wonder he was cranky, it looked like it could have filled his whole tummy!" We decided to keep the appointment anyway and took the cats to the new vet and I love the place. They are a cat only vet, friendly, pretty inexpensive, family run, and down to earth.

The new vet wanted to see both cats for the first visit. Zel was actually very well behaved while our calm one, Eva, earned a "W" in her folder because 2 people had to hold her while she was examined. She was an unhappy cat.

The vet says they are in incredibly good health for their age and weight is not a health issue with either of them. She said she's not concerned in the least about it and wouldn't be unless they each gained a few more pounds. Great news especially after the other vet was upset Eva was a couple ounces heavier than he would like and put them on a pretty strict diet. Which brings us to the issue.

After talking about his behavior problems the vet was pretty sure he has a food anxiety problem that affects only a small percent (like less than 2% small) of indoor house cats. Some, like Zel, go off their rocker as soon as their food dish is empty because they think "OMG I'm going to starve!" Since she isn't concerned with their weight she said to try our best to not let them see the bottom of their food bowl and we'll go from there.

At first I didn't understand how this could be it. Their eating habits haven't changed for two and a half years since the other vet awnted them on a diet. Zel's bad behavior only started at most a year ago, and didn't get bad until recently. After talking it through with her it made sense though. We've only been in the house since May of '05, so he's only seen other cats (well stranger cats) for that long. With them added in the equation and how he got worse after the thaw this year it makes sense.

So we tried it. After three days of keeping the food bowl full, a year of evil spaz kitty is gone. He still is not a fan of having his litter changed, but he's been like that since birth. They still share their box fine and he isn't as upset when the litter is changed. There's been no more peeing on our clothes and he's not biting or hissing or spitting or attacking randomly anymore. If anything he's gone back to acting more like the sweet cuddly cat I knew he was. My husband has even caught him throwing his litter around like confetti again recently. Not that I enjoy cleaning up the mess, but it shows he's a happy cat again =^_^=