I have done some tune up tasks to am '84 244 that I just bought for $250 with 100,500 miles on it...(new plugs/wires/cap/rotor, flush tranny, new air filter, and thermostat (other broken). The car starts up fine but struggles to idle smoothly speeds up then down up then down. It revs fine while parked but in gear while driving it is very sluggish off the line. Some on the forum have suggested replacing the vacuum lines, but I have no clue how to do that. What sizes are the lines I need to buy. I am not even sure where to start and how to identify all of them...there are a lot of tubes under that hood! Any help out there?

Jeff in SLC

Vacuum hose is just friction fit (slip on connectors) there are not very many of then. There is only a foot or two of the hose on the 85 and up 240, I'm not familiar with the 84 but it should be the same

Clean the throttle body, Idle air control valve and flame trap to hopefully cure the idle problems.
Dan

Check the main intake hose for cracks first, or just go ahead and replace it all together. Then check your pcv system. It might help to give the throttle body a good cleaning too. Also check the intake manifold gasket with some wd40 or other flammable (but not too flammable) spray.

Edit: I'm not too familiar with LH 2.0 (if your car is non-turbo) but you might also want to check the throttle position sensor when the throttle body is off the car. I just replaced mine on my 89, and all of my idle problems are completely gone : ) Turns out the switch was broken in both wide open and closed positions.