I recently traded for a 91 rs that has had the 305 replaced with a 350tpi. Starts up fine but sucks alot of air and if u were to drive off there would be alot of hesitation unless you let the vehicle run for 6 or 7 minutes. After this, it drives fine no hesitation but if I turn it off and instantly start it back I will have to wait another 6 or 7 minutes. Also smell gas while idling. Any help would be appreciated

 

Id check and make sure everything was traded out properly. Check fuel pressure, injectors, EGR valve, make sure all vacuum lines are going to the proper location..stuff like that. Someone might have also put in the wrong injectors. Can be easy to confuse the injectors from a 305 and put them in a 350.

 

I would run thru sensors and make sure there and plug and working
check plugs and wires etc
then check vacuum lines
also check if intake installed correctly
check fuel pressure

for gas smell did the hook up evap ?