Ps2,

I've tracked your car across 3 sites and see no report on your fuel filter condition. Have you determined it's clean or did you remove it and find evidence of tank deposits?

What's the O2 status when out of circuit?

JimF used the term "crap shoot" on the rebuild. He's right, and a proper disclaimer. The car has a troubled history as you've described. Think of what part(s) dates back to the prior owners woes. Things like the F-distrib. do fall in that range but is a guess.

Before ordering a spendy part, you need to recheck the basic stuff. Actual vacuum tests with a gauge. Squirting cans of various products is a method but leaks hide. Fuel pressure readings would be of value.

The O2 sensor is suspicious from contamination how much SeaFoam, Tecroline and other VooDoo chemicals has she drank? Is the EGR valve stuck open? There still are some easy but critical tests.