'91 celica runs poorly after timing belt job

I recently bought a '91 celica gt with a 5sfe engine that ran fine but
leaked like a sieve. No big problem, since I got it for a fraction of
blue book and figured I could fix it up and still come out ahead. I
replaced the front crank oil seal, cam oil seal, oil pump o-ring, oil
pump gasket, and oil pan gasket. While I was in there I put in a new
timing belt. The problem is that when I start it up now, it runs poorly
(though still idling at 1000 rpm, which is where it was before), black
smoke pours out the tailpipe, and the spark plugs are fouled. There's
also water dripping from the tailpipe at a rate of a drop about every
two seconds. These are all new problems. I thought I had the cam timing
off, but the markings on the cam gear and crank pulley line up like
they're supposed to. I also checked that I had the firing order right.
I never messed with the ignition timing. Would the car run like this if
the cam timing was off just a little? What else could cause these
symptoms? I seem to have gone from a car that ran well but leaked half
a quart an hour to a car that doesn't leak but also doesn't run worth
much.