Mystery diagnosis

I posted before about my 2003 Ram 1500. I just had a mechanic look at it today. He ruled out a lot of things, but it still isn’t running right.

The code reader said three of the cylinders were misfiring and the camshaft and crankshaft sensors were bad. He replaced the sensors and all the spark plugs. Afterward it didn’t show and codes. He said the O2 sensors were fine. There didn’t seem to be a MAF sensor. He said it wasn’t fuel supply or electrical. The exhaust is unrestricted. He thought it might be a lack of compression or that it needs a new head gasket. He’s coming back to test the compression, but he’s not sure what it could be.

You have to give it a lot of gas for it to start and it will die at idle.

Are there any other ideas? Maybe the MAF sensor is in an unusual location?