Can anyone recommend sampler vsts that do audio warping

Again, Groove Clip looping (CTL-L) should do, you should not need loading it in a sampler. Kontakt does it, by the way. Anyhow, try bouncing it to clip first, then groove clip it. If you do not get expected results, open it in the Loop Construction view and check if transients, original tempo and number of beats were correctly detected. If not, correct them manually. BTW, I am assuming that your sample is rythmical material with transients that you need to follow project tempo. If it is not, just time stretch it.