Transmission problem, please help! PKRWUD!!

[exgmguy]

I just switched from a T-5 to a C4 with a 3500 converter. At part throttle it shifts from 1-3 very early. Like 50 ft. from the light. At WOT the 1-2 shift is just firm, not a kick in the butt, and it flares on the 2-3 shift.
The I tried manually shifting each gear around 4000 rpm, at very light throttle. 1-2 shifts fairly firm, and it it still flares/slips going into 3rd.
This may also have something to do with it. At idle the transmission is quiet. But when I put a load on it, (driving, footbraking,..) it makes a rapid ticking sound. Not horribly loud, but definitely audible.
I have no clue when it comes to automatics, but I was guessing (hoping) that maybe the trans filter is clogged, causing the pump to cavitate and tick, also causing low line pressure that would give me a mediocre 1-2 shift, and the slip in 3rd.

I bought the trans from a Corral member, and he says it is fresh, with only a few thousand miles on it. I am waiting for an email reply from him about the history of the transmission.

Thanks for any help you can provide.
Rob