Does this have the electronic EPR regulator,looks like an impco model j on the front and is almost 10-12 inches long? Is possible that the electronics are acting up yes.....did you use the correct rebuild parts for this,know it LOOKS like you could use model J or COBRA rebuilt parts but am sure they are very diffrent....i believe this system also has what are called fuel trim valves,is possible that they might be giving issues......