The car idles fine and works great cruising around but when I floor it the engine pulls real hard up to 3000 RPM then starts to break up and will quit at about 3300rpm and I have to let off the gas.
I thought that the problem might have been caused by a plugged cat. The brick inside was broken and ratling around due to the car running extremely rich before the carb was rebuilt. Today I had a new cat put on and the problem still exsits so is it something with the carb? Thanks.

 

I am having this same problem right now with my explorer. It just got back from the shop today after 4 days.
My fuel pump wasn't putting out enough pressure when accelerator pressed. They tested it with a gauge and it was losing compression.
I had the same problem but was limited to 2500rpm's Ran fine up until then.

Not for sure its your problem but it sounds the same as mine.

good luck

 

Fuel supply is a good first guess. 87's had both an in-tank electric and a mechanical fuel pump. Make sure both are operating properly.

Another possibility is a problem with the secondary fuel metering. It isn't unheard of for the AV to open without pulling the rods out of the secondary jets - either from a broken AV cam, or loose hanger.

 

Thanks five7. I know what the hanger looks like but what is the AV cam? Should I just flip the secondary lid open with the car off to see if the hanger lifts the secondary rods or is this something I should do with the car running? How can I tell if the AV cam is not working.
Checking the fuel pressure would be second right now since I don't have a gauge.

 

Door #1. Flip the AV open while the engine is off and see if the hanger pulls the rods up. You can't do it with the engine running because the choke pull-off will hold the AV closed (assuming the choke pull-off is operating properly).