No, that is the kind of recommendation I would expect a dealer to use on an unsuspecting owner. Having just dealt with a mystery misfire, I will recount the issues. First, I would not trust a vacuum test alone to eliminate a vacuum leak, without also checking the torque on the intake manifold bolts, which are known to work loose. Plus, the old test of spraying starter fluid around the manifold while looking for an increase in rpm is another check. After that, you will want to eliminate: (1) the injectors; (2) the coils; and (3) the spark plugs. A decent mechanic can check these without buying all new parts by swapping them to different cylinders to see of the misfire follows the parts or stays with the same cylinders. All that costs is a labor charge. It could also be wiring to the injectors or coils, but with misfiring on opposite sides of the engine I think it unlikely. Ditto for the computer (PCM). If you are not overheating, and don't have coolant in the oil or vice versa, I would not expect it to be a head gasket. And again, you are experiencing the problem on both sides of the engine, rendering head gasket failure unlikely. I also experienced a short circuit in the wiring to the MDS solenoids that control cylinder deactivation, which are located under the intake manifold. For me, it fried all of the solenoids as well. That caused widespread misfiring on multiple cylinders. However, your cylinders no. 2 and 3 are not MDS cylinders, so I would not think that's the problem. After that, it gets ugly. My problem was ultimately the cam and lifters. Do some research and you will find a wealth of info on this fairly rare but known Achilles heel of the 5.7 hemi. In fact, it is thought to be more common on pursuit cars due to prolonged idling while on police service. Unfortunately, cam replacement is very expensive because unlike a traditional small block Chevy, Ford or even an old Dodge 340/360, the hemi's heads must come off to get at the lifters (which can otherwise be replaced on an old engine by just pulling off the front of the engine and the intake manifold). Thus, you are looking at new head gaskets as well. Plus, the heads should be checked and possibly rebuilt while they're off. In addition, you would not want to do a cam and lifters without a new timing chain and oil pump. Regarding your "cold start only" issue, my misfire was only at idle and only occasional, since I caught it before full cam failure mode,. So you can't necessarily rule out cam failure just because it only happens on your car occasionally. If it is a cam starting to go, you may have luckily caught it in time, because when a cam goes full failure it spreads metal throughout the engine, almost requiring a full engine teardown. There's other stuff too, but that's down the list as far as I am concerned. I would look for a shop equipped and willing to do a full engine rebuild, since it is distinct possibility. Good luck.