(My condolences on your loss btw...
I'm suspecting the TSP here...ONLY because it needs to be rinsed multiple times!
It's a great cleaner, but thorough rinsing is critical. Even a little residue will mess up a great primer/paint system. Not to mention waiting for everything to dry-out enough b4 priming!
Your prep sounded perfect...that's why I'm suspecting TSP residue here.
I'd use POWDERED Dirtex cleaner instead. Normally it doesn't need rinsing unless you've generated a lot of dust from sanding; or, the wash-water is getting fairly dirty.
What primer/paints are ya using?