Quite possible. My experiment with a 2006 Mustang 4.0 V6, after warmed up, hit ~3500 RPM, all warning lights on, flashing CEL. Take it in no codes stored. They did not test drive it, so CEL not triggered in the shop. My solution, drive around the block, trigger the CEL, did not turn the engine off so shop could see the CEL. Then they got a code. Bad ECU, perhaps that also was responsible for not storing the codes.
A shop tech might be excused for not taking the car for a test drive first, unless they were specifically asked to do that. But youād think the prior incident would have at least left some history codes in the computer memory. Even w/no test drive, I would expect the shop tech to check for history codes given the complaint. .
I provide whatever information I have but I donāt insult them by telling them how to do their job unless it is obvious what is wrong. Handing them printouts of all the responses on this site to me would be not only insulting but could lengthen the diagnostic time. Often there are opposite views here.
When I had problems w/my VW Rabbit ā before I decided to learn how to fix them myself ā Iād usually leave a brief note describing the problem, current symptom, & what Iād done to that point, note left inside the car. It definitely seemed to assist the mechanic doing the work.
Printouts of random ideas from an internet forum website, seems tacky & confrontational, not something Iād do myself. Were I using an internet forum for ideas, I focus on just one of the ideas and word it myself, very briefly, in the note Iād leave for the mechanic.
Welcome to the forumā¦ And thank you for the information you have given usā¦ Normally all we get is āCar have no powerā or āCar wont startāā¦ So very nice to read a complete sentenceā¦ lolā¦
I agree, only tell the mechanic what the symptoms are and when you notice it happening, raining, very hot outside, very cold outside, how long you have to drive before it acts up, the more details the betterā¦
But as soon as you tell the mechanic a bunch of guys on a forum said it could be this or that he will be thinking if you know what is wrong then fix it yourselfā¦ Donāt suggest it could be this part or check that outā¦ Kind of like telling a Chief/cook how much spice to put on something or how to properly season the food, or you cook it a certain wayā¦
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Hey, I totally agree w/you! Never a good idea to tell the mechanic what to fix, just provide symptoms. But your example was perfectly timed for me. I went to a steak joint last night that is known to over apply (by my standards) what they call āprairie dustā to their steaks so they are totally encrusted and practically inedible to me. So I routinely ask the server to ask the chef to use light dust please. They comply and we like it that way. Then they get a good tip and we keep coming back 
Tell a mechanic to replace the thrombostat in the wobbulator circuit and they will. Then they fix the real problem and charge you for both. Best to let them diagnose and fix as you suggested 
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Car has random cel. Car has noticeable misfire/shake. It is fine at shop. No codes. I bet shop 3 will succeed
OP needs to call the shop and tell them she is on her way but try to get it to act up on the way there and if it acts up DON"T turn the car off so the mechanic can check live data while it is acting up and see what if any codes are presentā¦
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Did they check the engine mounts and look for possible sticking brake caliphers?