I'm wondering if anyone has any susgestions as to what to do/where to look next....
About 2-3 weeks ago I started getting a strong exhaust smell in the cabin. It started out only when I got on the throttle hard, but now I get a slight smell in the cabin most of the time and if I get on the throttle it gets stronger (just like when it started).

The weird thing is it dosen't happen all the time, I'd say 60% of the time.
I just installed a ER TP last weekend, but this was happening before the TP and since installing it it seems to have stayed the same (maybe slightly better). I've checked/re-checked all the flanges/gaskets. When I was under the car (and put it on a lift) I couldn't find any black marks or exhaust leaks. I even had a shop check it with a stethoscope and they couldn't find anything as well.
I'm taking it to another shop or two this weekend to see if they can solve it, but does anyone have any susgestions?

-Jesse