car is running like crap

[Spln_Hrd]

ok my car has been running like sh!t the past 4 months and i have asked a few times but don't really get many replies.
when i stomp on it and it hits boost it back fires and blows black smoke and looses ALL POWER it won't even accelerate, the car jerks back and forth alot.
it is worse in higher gears, first is very bad but 3 and up SUCK.
i have hit fuel cut a few times and i am thinking it might have retarded my timing.
i also put in a larger fuel pump and havn't done anything to lean it out and it has ran worse since.

when it is like 50 degrees my car runs really good.

any ideas?

 

[hornetsnest]

Too rich???

What kind of injectors and fuel control are you running?

 

[evotuner]

Sounds rich to me. Like Hornetsnest said, what injectors do you have? If you still have the stockers, it should run fine even though you have a 255 Walbro. If you think your base timing is off, check it. Get some sort of fuel control, and have fun!