Exhaust vs Timing, something else?

[Krem]

So car has been degrading in performance for last couple of months. She used to have a nasty noise around 4000rpm and has moved down to ~3200rpm now. Noise sounds like a turbo spooling with a bad bearing, except I don't have a turbo.. After running warm/hot and parking for 15~20 min, she won't want to start back up.. she'll turn over, drop idle VERY low and stall out, then I can smell a funny exhaust smell in the cab. I can get her started if I give it a good amount of gas while turning her over to prevent the low rpm idle. Finally, the headers have been glowing red the past couple of nights after a 12 mile drive home from work where she sits all day.

I'm thinkin it's the exhaust system somewhere as the symptoms first began when I got my car back from a trial and error diagnostic repair where some mechanic pulled the o2 sensor and they did my timing. Not sure which timing they did, but I do know they had to replace my distributor and open the timing case, so another reason I am leaning towards exhaust system more so than timing. Wondered if anyone could confirm, deny or propose a more likely cause.