It would help if I put some info to diagnose from.

88 Bronco, C6, 351W EFI

new Accel 24lb injectors
new Distributor cap
new Distributor Rotor
new Plugs
new Plug Wires
new Intake, Throttle Body, IAC, gaskets
cleaned IAC valve (if its still working)
cat's have over 180,000 miles on them.

Thanks