Mitsubishi Repair: 2000 Galant, vacuum leak, position sensor

Question
I am getting a miss at idle and a stumbling on acceleration. On inspection I noticed a crack where the throttle body flange connects to the intake manifold. If the engine is running, and I gently move the throttle body, the engine stumbles badly and almost dies if I don't let go. I am guessing that when I am at a dead stop and I step on the accelerator, that the cable is pulling hard enough to open the crack wider and letting air get sucked in causing the hesitation. What do you think?? I think I can replace the intake manifold myself if it is indeed the problem. Would this also cause a miss at idle?? As far as the hesitation, sometimes if I am at highway speeds, and let off the accelerator, and step on it again, I get the same stumbling problem. If it is the intake manifold , how could this happen? I had the car worked on recently and they did a terrible job. Could they have cause the damage (The intake manifold was removed for the work they did)? They also cracked my cam position sensor and put in a rocker arm shaft in upside-down. Needless to say I am never going back there and never see any customers at their shop. Is there something else these idiots could have done to cause the problems I am having???

Answer
Cliff: First off if you are going to do work on your car, you will need a repair manual. You can buy one of these at any parts store for around $20.00 and well worth the money. I so hate shops that do shitty work, but there are such places out there. I would replace the throttle body, any vacuum leak well the engine is getting to much air. So the computer is reading things wrong, so your engine misses at idle, stumbling and what not. I would bet that, the shop broke something putting it on or maybe taking it off. You know if a bolt was stuck or something, they forced it. So it broke it sounds like a place that really did not care as long as they got their money. If they cracked the cam position sensor, you will need to replace that too. I would check stark plugs and the wires, if one wire has a break in it, well the stark would be going someplace else and not to the stark plug. Which would could cause a miss at idle and hesitation. A good tune up would be in order too and also you need to check to see if any of your vaccum hoses might have leaks as that might cause your problems too. I hope this helps and good luck! Linda