-Following seem to have same issue with my 4.8l swap. basically a stock tune with vats gone and some minor adjustments to trans and startup flare. Runs great until 210 then it acts like it retards timing something fierce past 40% throttle its gutless and will not downshift. I had this tune on my 5.3l in the donor truck and never had an issue, swapped over to 4.8 changed cylinder volume and engine displacement and this became an issue, also might add i moved from Michigan to Tennessee and the humidity and temperature change definitely played a part. New to tuning in itself but i have a decent amount of experience and knowledge in engine performance any help is much appreciated
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