Two items come to mind.
1. Have you ever replaced the fuel filter? It could be clogged.
2. How about a tranny fluid flush? Those torque converters can really cause problems.

98.5 SE Sport badgeless, MTX, KKM, SVT exhaust with resonator intact.
1985 Z51 Vette with many mods. Only used when the Tour appears to be outclassed.