had the timing belt replaced and drove vehicle 4 times after. It started bucking on highway. Took it back to mechanic that did timing and told them there was something wrong with the timing. They diagnosed it and said it was the distributor. They replaced it and it ran fine for 4 days then started bucking again same exact thing as it was doing before they replaced the distributor. Had the spark plugs replaced, all new wires, fuel filter, crankshaft sensor and still no fix. I thought it was timing related again as a mechanic advanced the timing to 30 so I could drive it home 500 miles to take it to the original people who did the timing belt and distributor. It has been in their shop for over a week and they have hooked it up to all scanning machines and the vehicle is not throwing any codes, they are puzzled. I need to know if it is possible that this engine which is a Nissan is propiatory and only likes Nissan parts ie: Hitachi distributors only?