check the mass sensor & check your vac lines. if you have an autozone near you they usually will do the handheld computer for you. & if your grand is like my 93 cherokee then you can do the self test: you run the vehicle for a few minutes in park then run it up to about 2000rpms & kill it..then you turn the key from off to run 3 times without starting it..on the third turn to run leave it there & watch the check engine light. it will flash codes. you can look them up that may help too.

93 xj stroked 4.2 w/4.0 head avenger supercharged 6.5" long arm 35" buckshots rubicon 44's front & rear