Haha, Suprahero ...I can just see someone with stock injectors throwing a lex AFM on there to drop the AFM hz (yay, no more fuel cut!), then using a SAFC to raise it back to what the stock AFM would have been outputting (hey fuel-cut, nice to see you again!). Tehehe.
...Loose clamp on the hardpipes would issue a rich condition.
Question: when it cut-off at 5k, was it obviously fuel-cut, or simply leaning out too much? You did have a wideband on it, yes? Scan up the sheet and let us see, it will give us much more to work off of.
I bet $$$ there is nothing physically wrong with your system, it is working exactly as you have built and set it, which is incorrectly.
Hypothetically, the lex AFM with upped fuel pressure should be a good way around fuel cut, if your pump is able to hold up, and you are able to set the necessary fuel pressures to work with the lower AFM signal. (remember, flow does not increase in a directly-proportionate relationship to pressure due to increased turbulence within the injector, but rather in an exponential relation) See below:
Using that, if you are seeing a peak of 48psi on your stock setup, and would like to increase flow from said injectors by 25% to match the lower hZ output of the lex-afm, you would need a peak of 75psi to work correctly with the lex-afm.
...again, with the exponential nature of the pressure/flow relationship, having a system mapped to compensate for a 1:1 FPR, you will have a grossly rich condition at the low-end of this system when your full-boost is tuned right. Where your old base pressure (no-vac) was 38psi, to increase the fuel flow 25%, with a 1:1 and fuel pressure to correct your top-end, your base pressure will have to be 65psi. ...sadly, you need ~59psi, so you'll have to either compensate pulling fuel (safer than adding up-top also negating the fuel-cut resistance of the LEX) with the SAFC or investing in a RRFPR (cartech/BEGI makes a nice one) to have the correct base pressure with the necessary pressure at full boost.
Honestly, I doubt your fuel pressure is where it needs to be when in boost. A, you simply added 25% more base pressure, instead of the necessary ~55%. B, your fuel pump may not be able to deliver 75psi at the flow needed when hitting 5krpm at full boost (You'll need one hell of a fuel pump!).
I'd have a fuel pressure gauge on there for-sure when going about it this way. Safer yet, would be getting a set of 550s and bringing your base pressure back down. ...injectors are ~$400, engine rebuilds are slightly more.
--billyM
