97 bonny trouble

in the last two weeks i have replaced fuel pump fuel filter egr plus wires ,coils,spark module,tps,pcv,cat. converter and my bonny still has a slight miss and a loss of power .the car works excellent when it is cold but soon as it heats up loses power and stumbles at steady speeds or inclines in the road.when i come to a hill the rpms jump up and down and the car sputters, on pressure test the fuel pressure is between 40 and 48 im running out of money and ideas to fix this problem any helpfull hints would be greatly appreciated thanks.

You need to have this car scanned during this event and utilize the freeze frame function so the operating parameters can be reviewed to help pinpoint the problem, guesswork will not correct this issue.

Have you checked for vacuum leaks? spray carb cleaner on the rubber fittings of your vacuum hoses.