I have a 2000 SSEI with a ZZP PCM, 3.4 pulley, 180 thermastat and a fenderwall intake. What should be the next step to gain some more horsepower.

rockers, springs, pushrods

ported charger

PEM'*

pick and choose from that list

Do you have access to a scantool? Its possible that you may be getting some KR (knock retard) from running a 3.4 with no exhaust mods.

A high-flow cat is usually a standard recommendation for running a 3.4, especially during the warmer months.

How can i tell if i have knock retard? :?:

you need a scantool to check

And what does it mean when the car is running at about 2500 rpms and the rpms jumps down and back up.

Were you driving? Did it shift?

Are you in Maryland? If so, there are several scantools owned by members near you.

Ya it shifts fine and ya im in P.G Maryland