Why is the diagnostic taking so long? on 1999 Chevrolet Suburban 1500

Today is Thursday and the shop has had my truck since Saturday. Each day I call they are telling me they are trying to narrow it down. One day they tell me they think a rocker arm is broken and the next that it is an electrical issue. I asked very kindly if this job was outside the scope of their expertise, but was assured that they had certified master mechanics and they will find a solution. Never had anything take this long before. Should I move the truck to another shop?

Asked by for the 1999 Chevrolet Suburban 1500
give them a time frame to work on vehicle,if not diag by then seek a 2nd opinion
1 more answer
Unfortunately today it happens that a vehicle can present with a problem that does outclass a shops abilities. Top techs use equipment like PICOSCOPE, pressure transducers, and all of the common tools as well as scan tools to troubleshoot everything today. Many who would be recognized as masters in the past have fallen behind and often don't even know there is a better way. After this long its time to move your car.
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