I have been working on my 1980 D50 Sport for a little bit now. So far I have replaced the radiator, done 2 oil changes in the past 2 months (mostly due to the fact that it hadn't received an oil change in probably years, and it was already black after a week of driving). I have had some work done on the steering and front end. As well as run some fuel additives through some premium gas.

After all this work, not that it's that much, but she sounds much better at an idle. However when driving, just feels like something is holding her back when I hit the gas. Almost like it still has the e-brake partially on. I know that it isn't the e-brake because when I put it in neutral and coast, it coasts just fine.

I have a Fram air filter in the air box right now, but I have considered getting a K&N, thinking it might be an air flow issue. I don't know where to start on this one. Any thoughts?