Silverbirch. Did you ever resolve this "boat anchor" issue on your 99 Tahoe? I have 99 Suburban with EXACTLY same issue. Higher I get into the rpms the less "seat of the pants push" I get. My buddy just bought 99 burb with 30k more miles on his compared to mine (215k vs 185k) and his has WAY more power. His burb is all same as mine as far as gear ratio and tire size. PLEASE let me know. Been chasing this issue forever. Thank you!