340 tunnel ram issue

checked plugs, changed plugs, same issue. and it wont go at all down the road i am lucky if i can move it to and from my garage. it will idle still but seems like still missing, but as i stated before anytime you go to let clutch fully out and give car gas "1k - 2k+ rpms' it will spit and sputter and jump hop and stop, backfire you name it! if you dont try to move car it will do about same when giving it gas off and on. but sometimes it will seem like its fixed and you go to move it and back to square one. i will get carb info tomorrow and also test for vac leaks.