2002 Saturn L200 missing engine

The Saturn stated to miss about 10-12 months ago, and I took it to a local repair shop to get it fixed. They replace all the wiring & plugs, as well as other modules, but within a month the car started to miss again. I took it back to them, & they said they were not sure what else they could do. I tried gas supplements that seem to help some, but did not cure the problem. Amonth ago, I tried a new local repair shop, Cortez Auto Pro # 3, and the again replaced the 4 spark plugs, which the manager said the really needed to be replaced, & the Valve cover gasket as well as the Ignition Module. The car seem to run well when I picked it up, & I drove this car approx. 100-200 miles since I picked it up, and all of a sudden it started to miss again. I took it back to Cortez yesterday, & the service guy told me that the care would be fixed without charge. I called him late4 yesterday afternoon, & he told me that a ingnition module needed to be replacedd , but it was different than the ignition module that had been install before.

With this information; Are these guys trying to get to me, or this is a possibility.

Thanks,

Ed Spicer