Hello fellow gm lovers!

I have a red 98 gmc c1500 p/u 5.0L and I'v owned it for almost ten years. It has over 200,000 miles and I still love it despite minor problems with it . Iv put in two water pumps two fuel pumps new ignition switch a new rear wheel cylinder and lots of other things like door handles and windshield wiper motor . I just put in the second fuel pump and now it Boggs down when holding a steady speed . It doesnt stall but i know that's not normal. The obd11 scanner is saying I have a small leak detected and an evap fault . Will this cause my symptoms?