the tach suddenly dropped to zero for a few seconds?

I maintain it in accordance with the owner's manual. It's been quite reliable until recently. Three months ago while driving on a highway, the tach suddenly dropped to zero for a few seconds, but the engine continued turning and no warning lights cane on. The tachometer then came back up. I thought it was a fluke. A month later driving in heavy traffic on an expressway, the check engine light came on; Rpms dropped off, and shortly after the engine quit. After a short while, thinking perhaps the transmission had gone, not the engine, I started it up and drove it to the Firestone service center - the nearest Acura dealer is over the bridge in Brooklyn. After seeing, the transmission was fine. Firestone thought it was a fluke, as they did not replicate the stalling. I had the car tuned up, fuel filter and oil changed. A month later, the tachometer again dropped down, I gave it the gas and it went back up. As I slowed for a light, the Rpms again dropped, the check engine light came on, and shortly after, the car again quit. When I tried to restart it, the engine turned over but would not fire. I called for a tow. After waiting about 30 minutes, I tried it and it started. After it was towed to, Firestone They did a computerized engine analysis and said the engine control module was not showing any bad codes and it was fine. They determined the distributor assembly had to be replaced, as it not giving a spark. They said the igniter in it was bad. They also flushed the fuel injection system. I drove the car on a trip of 100 miles and it was fine. A week later on another trip to New Jersey, on the return the same sequence occurred - check engine light, low Rpms and then the engine died. Again, I was not able to restart it. While waiting for the tow, after leaving the engine off for an hour, it would restart. Firestone tried to duplicate the problem for two days with no luck. As the distributor had been rebuilt, they thought that the replacement had a bad coil, as the problem seemed heat related. However, they couldn't explain why I drove 100 miles problem free. They replaced the distributor assembly. I drove it home, but am now afraid to drive it thinking it might be something else that could leave me stranded again. I don't know whether I should just have it towed to Acura and have them charge a fortune to see if they can figure something. It's so frustrating thinking the car may die at any minute if the distributor was not the source of the problem.