brand new built 4l60e slipping off the line???

[big72red]

I just installed a brand new 4l60e built by a company called Performabuilt into my 94 Z71. Actually, I've done it TWICE! After the first installation, the truck was sluggish off the line. Engine would rev to about 1500-1600 before the truck would begin to move. Seemed to shift fine otherwise. It acted like it had a high stall converter in it. I did some research only to discover the trans builder sent me wrong converter. They had sent a 2000 stall converter. After a couple of arguments over the phone, I ended up exchanging it for the 1600 stall I had ordered in the first place.

Finally got a chance to swap the converters last night. The truck is behaving EXACTLY the same as it did before with the slightly higher stall!!! Fluid level reads perfect, pump is circulating fluid, and seems to shift fine once in motion. It just does not want to get moving from a stop or very slow roll(below 10mph). If I ease into the throttle on flat ground it climbs to about 1500-1600rpm then it starts pulling. If I hit the throttle any quicker, it flares up to about 1800-2000rpm and hits fairly hard...like side stepping a clutch at 2000rpm.

I was told it would take approximately 12qts to fill the new trans. It's only holding about 8qts before the stick reads overfull??? I tried adding a couple extra quarts to no avail. You guys have been very helpful in the past, so I'd greatly appreciate your insight on this matter. I'm out $2500 for the trans, $250 for the second converter, and about $200 worth of Dexron VI fluid, and this thing is still sitting in the driveway! Thanks in advance for any light y'all may be able to shed on this issue.