Hi guys. Have rebuilt the 454 in My 87 Saltaire after having 2 bent conrods. If I give it full throttle it takes off perfectly but at about 3500rpm with full throttle it stunts/dies like pushing the choke on an already warm engine. If I pull the throttle back a little it is fine but if I push throttle on further it stunts. I had the car by serviced thinking it may be the car by but didn't help.

Any ideas please.
Thank you.