First attempt was a fail. I put too much solder paste on and some got some under the chip and ended up shorting some vias. Yea, way too much.

Second attempt went way better. A few bridges, but easily cleaned with some solder wick and hot air.

Cleaned up the flux, threw it in the test bench, and IT WORKS!!! Completely resolved the 256 color issue.

I guess there was some internal failure in the 5434. Wow, what a saga. Huge shout out to everyone who helped me in this thread. Really appreciate it!

Hey, this is fantastic to read. Glad to see that the problematic part was figured out.

I find I have another Trident card that is leaving some individual pixel trails when blitting.. now I'm starting to ponder if it might be a chip failure on that one as well... hmm.