1987 350 Tbi Back Fires Really Bad When I First Start It

[haulincats]

I have an 87 Chevy with a 350. It is the TBI (I believe the 1st year)

I only drive it on the weekends. When I start it after it has set for the week,

it back fires really bad. After it warms up it runs really good.

I put new plugs, plug wires, cap and rotor in it and it still does it.

It does sit outside.

Any idea what is wrong?

Thanks,

Vance