Torque conv. vibrations 3rd gen.

I just had a new crate motor and 700R4 with a 2400 stall put in my car just 1500 miles ago. It has always seemed not right to me but since I have not driven a car with a stall conv. I wasn't sure.

Well one morning I started the car and instantly noticed the trans felt different. Like its holding the engine down. When it goes into OD, lock up, and I press the gas a little like to pass someone there is major vibrations now. And the car has slowed down drastically.

I bought the trans from Mad-dog transmissions. So I'm sure the torque Conv. is a no-name. Should I just get a quality conv? Is this the prob from what I explained?

EDIT: I had some part installed so it won't downshift from OD unless you give it at least 75% throttle.

Sounds like the converter clutch may be slipping some. Depending on how you have lockup set to work this may be your problem, Since you have the sleeve installed for kick and probably havelock set to come on in third and or fourth gear, Unplug the electrical harness from the trans and see if this condition goes away, Dont drive it alot like that though at least no on long trips , If it does go away you might want to consider getting a vaccume/speed operated lockup kit. I would also check fluid condition in case the converter clutch has allready started to burn up, The converter clutch was never designed to come on under heavy throttle load and may not be able to hold it,

I'll check that out. Yea I parked it and am driving my Mach. Hate putting miles on it. Thanks.