HELP! 94 auto no lowend power and backfire

[91lxvert]

My sisters car has like absolutely no power below 2500 rpm, it backfires and pops and then finally when it gets out of the slump takes off. It feels like its loading up then when it finally burns the fuel off it can go.
The car was having issues similar to this where it would stumble from tack off and die. It sat for a bit at my house, I did a tune up and such and it was running pretty good. Good enough to pass California Smog . Then All the sudden it started this crap.

Had 2 codes, P1509 for IAC and the other code I don't remember(thought it was p0139, but may have been p1152) but i remember it was for bank 2 rich.

What I have done so far:
New plugs and wire
OHM'ed out the coil pack (all ports showing over 14K resist) and changed it to a spare that checked out fine.
Changed to different IAC that I cleaned.
Cam position sensor is new (had code a month ago for it).
Some of the O2's were replaced with bout 3k miles on them but dont remember if all or which ones)
Fuel Filter

Car idles fine, actually much better after the clean IAC and coil.

Was thinking about checking TPS but haven't yet. ( I have spares from a donor car = tps, hpipe, egr, O2's)

Anyone ever had these issues? Any advice is very greatly appreciated.

 

[MustangLX-5.0]

Three words "Cam Position Sensor".

99% chance the cam sensor is the cause. This is the third post I've answered in response to the same type of problem. In each one of these cases, the cam sensor at one point or another within the last month or 2 had been replaced. Same symptoms, (runs like total crap below 2500 RPM), same or very similar code (bank 1/2 rich condition) and they all hadn't done one thing.....synchronize the cam sensor with the crank sensor. It's a common problem. You'll have to take it in to a shop to have them synchronize it as a special tool is needed for this. I was a tech, but I never done this procedure. Not sure where the tool could be obtained except for those high end tool companies like Matco and Snap-on. Sure its probably expensive.