Newbie help on '87 GN Stumbling problem HELP HELP!!


New Member
Hi Folks,
I'm new here ,so go easy on me! Bought my car back in November, never rode it down road went straight in the garage.Just got done with the interior.
Took it for a ride this evening. Got on the throttle, it starts stumbling (Bucking) just going into second gear and almost stalled out. :mad: :mad:
I did read the posts, i'm confused:confused: where to began to solve the problem.The engine is modded bigger cam polished ports,bigger turbo, engine bored out and a custom chip, bigger injectors. I don't have all the specs in front of me. I believe the the car is pushing 450 to 500 HP.
I will have more info up for the specs what was done to it.
Can anyone help me out?????????? I will post a pic of my car once i wash and wax.

Thanks!!:smile: :biggrin:
Probably the coil pack. However, a bad TPS sensor also caused my car to stumble. Others have said a bad crank sensor could do it too.
Another possibility would be the MAF (mass airflow) sensor. A failing coil pack/module will usually start bucking hard early into boost.

A bad maf will usually start bucking etc. with even light accleration, and the more throttle you try giving it, the worse it gets to the point of almost stalling.
Thanks to all of you for the help!!!
Yes ,TurboDave this sound like my problem. Would this cause it running rich too.
My O2 sensor is black.