PR is the can at the front of the fuel rail .. over by the termo housing .. it has a vac hose hooked to it .
There should be no gas evidence in the hose or you have a ruptured reg diaphragm .. allowing both too high a FP and raw gas getting sucked into the engine .. so you can see how this would easily upset the A/F mixture .
vac leaks are just searched for , check every hose ,, suspect on that chassis are around the throttle/intake area and under the engine front plastic cover ,, the white plastic line going to the SOVs is infamous and many Techs just can that line and go with a full length rubber one [ the plastic ones crack and break from heat fatigue]