The 4th generation Volkswagen Jetta greeted the American public in 1999, and ended its distribution in model year 2005. It was the latest in a respected line of cars—the first generation being produced in 1979 after VW decided they should offer a sedan alongside the hatchback Golf. The fourth-generation Jetta introduced a streamlined rear antenna, a rounder shape, and also received a higher safety rating. It also contained a power increase from the earlier incarnations, and consumers were able to choose between two different internal combustion engines: the turbo 4-cylinder (AKA the 1.8T) and the VR5. Shortly thereafter VW issued a recall on the turbo 4-cylinder models due to coil pack problems resulting in cylinder misfiring.
Some signs that possibly indicated a misfiring cylinder include feeling unusual vibrations all the way up through the steering wheel, or the Volkswagen occasionally stalling out while idling. Another indication that something may be wrong is that the fuel-efficiency of the Jetta decreases significantly.
These symptoms can be indicative of other problems, but historically these point toward the recalled cylinder. Some other causes could be a faulty spark plug and spark plug wires, or maybe your fuel lines sprung a small leak, resulting in a too-rich mixture of fuel and air. On the more serious side of things, the coil pack itself could be dropping a spark due a crack. Fortunately, the recall makes this potentially daunting fix relatively simple to solve.
The best way to discover the specific issue is to take your car to a nearby VW repair specialist. They can check the vehicle over and tell you precisely where the problem occurs and help you decide an appropriate course of action. Also, if it is included in the recall, then the repairs will be covered by Volkswagen.
Search for a local, independent Volkswagen repair shop with Volkswagen mechanics that have dealer-level expertise at a fraction of the expense.