Dart not running right.

Ok, I will try my best to explain what is going on, and what I have done so far... What it does is it will run fine up until I get into 4th gear on the freeway and then it seems to not have any power, kind of just surges. I can hold it steady and it is not too bad, but it does seem to lose power and I end up slowing down. Now I can come to a complete stop and take of and it is fine until I get up to speed again, Ok, so far I have switched out the dist. as I was thinking that might be the problem, as have had problems there in the past. I have also changed the ecu and still the same thing. My set up is a 318 Elderbrock perforance carb, electionics ing. I am now starting ot think it might be a fuel problem, or maybe a bad plug or 2. Any ideas will be very helpful
Author: admin