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if they made any adjustments to the your engine or idle, this is suspect, also the fuel filter may be on backwards or have a leak that air pulls through, its not likely but maybe the fuel pump has started losing pressure and now the engine is freshened up and isnt getting what it needs to run. make sure the oil cap is on all the way and the air filter cover is secure, these would cause your syptoms. i would make sure the correct spark plugs were installed and that they were set to the appropriate gap. if there was no problems before you took it in and what you list is all thats done, it will be one of these problems.