K guys i need ur help here. Well my car was rungging fine but i just had my buddies in shop install a new edelbrock 600cfm carb on my car. Well i got it back and for some reason now when i push the gas like 1/4 the engine revs up and it shifts real hard at like 2900-3000 rpms. But if i hit the gas down around 1/2 pedal or more it shifts ok. Also, when i shift it from park to drive i get a real hard shift sometimes. Now the guy i bought the eninge from said he beefed it up a bit but how do i know this for sure. Were should i take it? i dont think it has a shift kit to it and it never did this with the old carb(it was a 305 carb and ran real bad). Also, when i come off the gas it makes sorta like a hissing noice.Please guys help and i sure hope it dont needa rebuild :-(. Its an automatic by the way. Any help would really be apreciatted