94 Peterbilt 3406c peec slow throttle

I have a 3406c peec cat (ser4ck16361) in a 94 pete that has for awhile had a hiccup when going down the interstate loaded or empty. It feels like it drops to zero throttle then comes back up in half a second, it's quick enough that I can't even reproduce the symptom with the pedal. But now I'm having an issue when I'm shifting it takes it about 5-7 seconds for the turbo to start spooling and for the truck to have power. Once it gets spooled it pulls fine(I haven't pulled a load up a hill yet but it's pulling the hills empty like it usually does tho) I do want to eventually convert to mech but for now I just need this truck to run.