Finally got my $500 eBay 78 ITC Fiesta on the track at Gingerman last weekend. Not on the track since 98. Handled and braked well but ran poorly. Starts and idles well, revs to 5000 well with no load, but stumbles/cuts out when revved under driving conditions. Ran ok at around 3000-3500 but not able rev above this. Following checked and/or replaced with no change in running condition:

Good compression
no smoke/minimal blowby
new plugs
new fuel pump mechanical- even tried switch to electric
new fuel filters
tried both new weber 34 DMTR and original carb with no change
timing correct
ran cool/ good oil pressure

I am not familiar with the electronic ignition on this car. Wiring is fairly cobbled up by prev owner.

Any thoughts on what to check out next?

Thanks,
Marc in Indy