just cant get the car to run right

If you decide to pull the intake, I suggest getting an after-market aluminum 4-barrel one. You can find for <$100 w/ shipping on ebay or even cheaper on Craigslist. Sounds like you can drive it now, so you have time to get a deal. That will be about as cheap as shop work on yours and will allow many more carb options. If a stock cam, daily driver, don't get bigger than 650 cfm.

For best mileage, a 450 cfm like the Holley Economizer is best. I got an almost new one for ~$40 I recall. If you want to keep some power, the spread-bore ones Quadrajet or Thermo-quad have tiny primaries for good mileage but bring it on when the large secondaries open. However, TQ's are getting rare and parts expensive. Longer term, consider throttle body injection like Mega-squirt, Howell, Pro-jection.