Runs "Fine" for a bit the leans out to undrivable condition. What's going on?

[JustJeff]

Looking for a little help from a kind soul. Car runs fine (within reason, it's in the ballpark) for a little while. Could be heat or time that triggers it, I'm sure yet but heat seams to be a fair bet, it's like someone flips a switch and it suddenly becomes undriveably lean. WB doesn't even pick it up it's so bad. Anyone know whats going on? Here's my tune.

It's a 5.3, 78/75, 80e, 80lb inj, stock cam,60psi fuel pressure, GM 3 bar MAP, no MAF, SD tune.

Also for the time being I have no IAT senor... Although I didn't think that would keep e from running and driving in the ballpark.

[5FDP]

When all fueling calculations take the IAT as part of it's equation, you really need that installed as soon as possible. You can't ball park something if it thinks it's at the north pole.

The P59's computers, atleast all the ones I've dealt with and seen with similar things on here will go into a cat test that can lean out the fueling and richen it up while trying to test for the cat/rear o2 sensor. I've always had to install the rear o2 sensor again and just zip tie the sensors out of the way. Or I'm sure there is a way to mimic the signal so the computer doesn't see an open circuit.

That's the most I can say without seeing data logs.

Side note, you don't want to zero out the maximum knock retard table. Because what if you really do have knock, now you'd have no idea and something could go wrong. If you're not running knock sensor, fueling and timing need to be spot on.