TH400 Torque converter going bad?

[eljefe73]

I've got a 402 with a TH400, it's dialed in with a Holley and HEI. Recently under load and low RPM, like pulling a trailer from stop or uphill, it bogs down. Not even revs up, or spins tires. other than a slightly hard shift (which i don't think is too severe) there are no other sympthoms. at a running stop, it'll still spin the tires down the block, but from a dead stop or load it'll bog down or lag. Fluid levels are good and not burnt. any thoughts?