My buddy has an 89 vert with 80k Miles that has these symptoms.

Car is hard to start hot or cold.

Strong gas smell while cranking and after starting.

runs very poorly until it warms up (like fouled plugs)

Won't idle or run under 3k rpm. It stalls under 3 k.

runs very smooth over 3 k after it warms up a little.

weird knocking coming from AFM while cranking. The bullit shaped door is bouncing back and forth. I don't think it's supposed to do this.

He let the car die and we could not get it started again.


We know we have spark on all plugs. We took the very dirty air filter out and it did not affect the symptoms.

It seems like it is just dumping a lot of fuel into the engine.

Anyone have any Ideas.

Thanks,
MIke

 

I lost my AFM once. So, if it is knocking, maybe you should try to find a used one and compare. The AFM cone could be sticking. Remove the AFM and see if the cone moves back and forth. Make sure it doesn't get hung up and that it moves freely. Make sure that the spring has consistent tension. It might be broken.

My problems were the same as yours. It ran like crap below a certain RPM and ran great above. In my case, the AFM wasn't closing all the way.
You will need new sparkplugs and oil after you swap the AFM. The oil thins out from all the cranking/flooding. I don't care for cleaning plugs unless they are brand new.

Also, the airfilter might smooth out the airflow through the AFM. Don't run without one and if you haven't already, get a new one.