Why does 1988 grand marquis hesitate when you accelerate hard on the gas and the check engine light comes on?
I had this issue my self with a 89 try loosning up the
distributor turn it one way a little start it up and keep doing
this till it gets better or worse.
Could be a lot of things. I'll make some assumptions, first that
the car runs fine otherwise, and maybe has a slightly rough idle,
and second that the codes being pulled do not indicate timing
1) EGR system Idle Air EGR valve Blocked EGR ports on throttle
2) Bad failing fuel injectors.
3) Torque converter lockup bad
What do the codes indicate?
Take to Autozone for OBD2 check.
May be air mass flow sensor, clogged catalytic converter. Dirty
fuel filter will cause dirty injectors and clogging of catalytic
AFTER ALL OF THIS IT WAS A RELAY RIGHT UN THE HOOD ON THE RIGHT
SIDE JUST HAD TO CLEAN IT.