My 1990 infiniti is running like a truck....WHY?

So my 1990 infiniti Q45 is feeling more like a truck then a car for some reasone. When I start it it just shakes more but it still runs, it only shakes if its in drive or if Im driving under 35 mph. Please help.

Let’s start with the easy stuff. When was the last time the plugs and wires were replaced? Does it do it more often when the weather is damp? How many miles on your Infiniti?

Is it an automatic transmission? If so has it ever been serviced? (fluid changed and filter cleaned)? When was the last time the air and fuel filters were replaced?