OK so heres the whole story, I got this truck running rough. Fuel filter was clogged, replaced it. Fuel pump worked sporadically, replaced it. EGR was gummed up, replaced it. PCV line was cracked, repaired it. Finally I got it running great with a new MAP sensor, and all was good for about a week.

Since then it has been running worse and worse. It has been bogging while revving, and there is a dead spot in the rps, by which I mean from idle, when I gas it there is hesitation and then it surges up. It was throwing codes 24 and 13, TPS and "No change in MAP output voltage from start to run". Just today it would not run at all, it would reliably start but then immediately die. So I slapped in a new TPS and code 24 went away, but still the same, start and then die. So I put in a 2nd new MAP and no change. Very very rarely I can get it to idle, when it does, it idles very smooth, but as soon as I tap the gas it dies.

I checked for vacuum leaks, none that I could find, but I haven't totally ruled that out yet. The MAP vacuum line has good vacuum, but even with the line disconnected there is no change, for better or worse. It sounds to me like I may be experiencing an extremely lean mixture, however I can't shake the idea that something electrical is causing this. I thought maybe the IAC might be at fault, but the majority of these problems before today involved bogging in the mid-upper rps, also indicative of a lean mixture.

So where should I go from here?

 

i don't know the 2.5L, but have a few questions that may lead to some ideas.

have you been able to check the ign timing point with a light? Using the light does it trigger on all 4 holes?
how do the plugs look?
are you able to pull the O2 sensor and try to start / run. (as a check for excess back pressure)?
fuel pressure is within spec during start attempts?
Are you able to check the TPS and MAP sensor harness continuity to the engine controller?