carsea wrote:
It spits from 2000 rpm to about 4000 rpm usually cruising never when I stomp on it, it backfires explosively when I get off a hard pull and let the transmission slow me down. Thanks for the help.
Firstly this is the internet and I can only go by what you write so here's my answer based on the statement above ...
Cruising at 2000 to 4000 RPM on a small throttle opening is pulling heavily of the idle circuit still and it seems too lean. If that's so it also explains your backfiring which is being caused by the throttle plate closed and drawing mostly a very lean mixture from the idle circuit.
So we have 2 separate evidences that you have a lean idle circuit. Most DCOE I have ever worked with seem to have a F9 emulsion tube with a 45 idle jets, factory standard it would appear, so you can try 55 idle jets and/or F12 idle tubes if you can get them. Obviously the jets will be easier to get and try.
Also if it idles best with the idle mixture screws less that one turn out that also tells you it's too lean, that might be a 3rd evidence but this isn't always 100% accurate as a lumpy camshaft can also be the cause.
So I say go and fit some 55 idle jets and see what happens.
If that doesn't help enough then next step is try some F16 emulsion tubes (if you have F15 currently).
This is all presuming that your car accelerates reasonably well and it's just the cruise and backfire that's the issue.