71 Dodge Dart Swinger in England

Well your making progress. Always a good thing. The thing about these old mopars is there so many people out there that think they are mopar "experts" that eff em up, and then guys like us fabo members have to unfuck them.

Could possibly be a manifold leak. Anything is possible. An easy check on that is with a can of carb cleaner. With the engine running, spray it where the intake manifold runners meet the heads. One runner at a time and see if the idle clears up for a few seconds until the carb cleaner evaporates. If the idle clears up then goes back to crappy where you sprayed it, then you have a manifold leak where you sprayed it. At that point order a gasket kit and change them out.

It can be a pain when buying something that somebody has done work to previously. Sometimes you just dont know how expertly something was or wasnt done, and you end up redoing it yourself for the satisfaction that its been done right.