Hi im trying to help my friend fix his 91 FC NT... The car only has about 40k on it and the only mod we have done so far is an intake. Oil was just changed about 200mi and spark plugs 4-5000mi ago. The car was running fine up until a week ago when it started having problems... it would have trouble starting and finally start after a couple trys. Everyday getting worse also his car was showing the Fuel Light on w/a full tank. It would run and start with ease after warmed up. Then today it wouldn't start my bro has a FB and i know how they like to flood. So i we pulled the fuse tryed about 5 times cranking still wouldn't start. We pulled the plugs and cranked ~wire brushed the plugs and the damn thing won't start. Checked the plugs and we are getting spark so i doubt its the coil paks. Anyways it has a good soild crank with a stumble like it wants to start then followed again with a heavy odor of gas. Spark plugs looked ok but did have build up from the oil inj, i believe and L plugs smelled heavily of fuel.
If anyone has any ideas id appriciate it
Jacob

 

Sounds like lost compression to me.

Intake-Compress-Ignite-Exhaust

So if all you can smell is gas and the plugs spark.... compression or a massive vac leak somewhere.

 

check all the tubes that came off your stock intake make sure they are plugged tight