Does anyone else run a high stall converter behind their pretty much stock 2.5? My van has a NAN converter that the previous owner installed and its driving me absolutely insane, draining my wallet too. This converter stalls at 4200 RPM and just makes climbing any hill slow and buzzy. Under normal driving conditions I never see less than 3000 rpm and my MPG is a little less than 15. When the transmission shifts the converter swallows up the shift and there is absolutely no drop in RPM, just a quick jolt and an exhaust note change. Under WOT it instantly shoots to 4200 RPM and stays there until the speed increases enough for the rpm to climb to 5K then it shifts, it's like driving a CVT. Also since it stalls so high, part throttle builds boost so fast is surges so its either stay out of boost or give it full throttle.
My theory on why it sucks so bad is because the converter stalls so much higher than torque peak, is that why? If not then why is it so sluggish?
I have a spare 5 speed, just need a clutch and everything else.