[V8] bogging down

[rmwoodbury at roadrunner.com]

I think you should check both catalytic converters.  We had the same symptoms on my wife' 100CS Avant and the problem was the converters. When they got heated up, they plugged and thus the "bogging down".  

Whenever I have had any of the sensors go bad it has always been a short term non-start when they were hot, cooling down the car would start normally.

If your prior owner ran the car with fuel or ignition issues for some distance the converters could have been fouled which caused them to age to the point that now one or both has failed.

just my .02....

Roger