Cadillac Repair: 89 caddy surging idle, vacuum leaks, vacuum hoses

Question
you guys have helped me before. 89 caddy fleetwood fwd 4.5 fwd. car was bogging down no power. mechanic replaced computer, cat conv, plugs[ 6 of 8 knuckles still bleeding]and gas filter. when i start car in morning the idle surges high rpm to low rpm. when i get to a stop light it feels like it wants to stall until with my foot on brake i give it some gas and it smoothes out. if i hit the expressway after about 5 mins. after starting it starts missing pretty bad but other times it runs like a champ.no check engine light. please help my wife won't drive it anymore and i want my truck back thank you

Answer
I wish I could help you on this one, But surging can be caused by so many things that it is impossible to list them all. The first things I would check is for vacuum leaks at any of the vacuum hoses and check the intake manifold for vacuum leaks by spraying it when COLD with carburator cleaner in a spray can that you can purchase at any auto parts store. This can also be used for vacuum lines to check for leaks. If you spray a certain spot and the engine smooths out this would be your leak.

CAUTION: try and not spray the spark plg wires as the cleaner is combustible with electricity.