5.3 LM7 Throttle Lag

[307iron]

Pardon me for being a newby, and asking a question that has probably been address many times, but after searching I can't find an answer.  I recently purchased a sand rail with what I found out is a 99-07 5.3L LM7 engine in it.  Being an off-road vehicle, with Super Trap for muffling and spark arrestor, there are no cats, or Oxygen sensor in the exhaust. The throttle body looks to me to be stock, and it has a cold air intake setup.  I was also told by the previous owner that it is completely stock, he also told me it uses the stock wiring and ECM.

Here is my issue that I am seeking help and advice with, the thing nearly quits when I press on the pedal from an idle.  It runs great once it picks up, and there isn't much of a problem with throttle responce at any other point after getting going.  I have even had it actually stall and quit.  I've tried cleaning the MAS and the TPS, but no luck there either.  I'm considering buying a 90mm or 92mm throttle body in hopes that this will fix it.  I hate spending the money if it isn't going to fix the issue.

 

Thanks for your assistance and knowlege