my car runs good when the SC is not producing boost but when i hit the gas and get around 5PSI the motor starts to cut out and pulse and the car has bad acceleration and hardly picks up speed around 80 not sure whats wrong i just had to drop in a new motor 100 miles ago now this
does any one know of any problems that would cause this could it be the CAT is so how could i test that or any other things that could be wrong

It could be a clogged cat. Try removing the front O2 sensor. This will allow the gases another way out and reduce the back pressure. It will be loud, and don't run like this for very long. If this runs better, you have a clogged cat. If no change then we will have to look at other options.

Hi Greg!

Welcome to the Bonneville Forum!

Please add your year and trim of your vehicle to your signature line. That way when you start asking questions in other areas of the forum, we all have a better idea on how to assist you. Click on "Quick Links" above, go down to "User Control Panel" and then click on "Edit your Signature" It'* pretty straight forward from there.

After you try what Dan suggested, let us know how it worked for you. If it didn't work, we will find a solution to your problem.

Being a 2000+ you are likely running lean. Every single 00+ i've scanned has been lean.

You need to get it on a scanner and code reader to know what is happening. It'* possible you are getting massive KR and that is holding you back.

i hooked it up to a scanner and got a random misfire code

Try checking the fuel pressure.

When was the last time the plug wires and plugs were done?

im puting some new ones on now but they were done around jan. this year

Had the same symptom and diagnoses, random misfire cylinder #5. Ended up being massive corrosion on the #5 plug wire, not on the plug end but on the distributor end. Removed the corrosion and the problem corrected itself.

If you are running lean what are some of your options to fix this?