Hello. I have had this car for 20 years and about a year ago the car started shaking on idle. I took it to Nissan center, they tested the engine, all running good. They changed the spark plugs, the car looked better for couple of days, and then went to the same. I took it to another Nissan center, they said it was bad injector. They checked it, injectors were good, but the main engine harness was not. Got a new one, the car looked fine, but couple more days and it's shaking again. Also, at high speed it looks like shaking more than normal, but not so sure about that, might be just me trying to overlook the issue. I don't know what else can I do to solve this. The start of the car is not the same every time. Sometimes it starts immediately and the rpm's stay down the 1000rpm and that's when it's worst. In the cold starts, also get a bit of fuel smell in the cockpit, I don't know if it's related with it. So, if anyone has any idea, please help me. Thank you

 

Bumping this because my 92 is doing sort of the same thing. Occasionally it will shake enough at idle I can feel it in the floor. Shake in 5th gear above 65 mph and sometimes a funky smell- almost sweet but not quite like coolant leak. Starts different every-time, sometime cranks right over and sometimes seems to struggle. Sometime smells of gas (or some fume) in the cabin.

Did you ever figure out if it was injectors or something else? Thanks.
- Jess

 

I would inspect the engine mounts.