94 Taurus engine shake after starting.
I have a 94 Ford Taurus GL 3.0 V6 with 140,000 miles. The vehicle shakes a bit, it feels like it is trying to down shift mainly when at an idle. I also notice it during slight inclines like on/off ramps, more than the usual down shift to make it up a hill, as well as speeds of 40 mph and under, city driving. I have mainly noticed it so far while the air conditioning is on so wondering if it may be somehow related? The last couple of days right after I start the car, it feels like the engine is shaking. Yesterday it only did it for about a minute while I let it idle before I started driving, but today it did while at idle, then I felt it periodically as I drove to work, about 5 miles. Just wondering what it might be. I am sorry if this seems vague. At first I thought it might be the motor mounts, but I checked them and they are fine. It is overdue for a tune up anyway, new air and fuel filter, maybe plugs/wires, clean out the distributor cap/rotor. I am going to start with these "cheap" fixes first to see if this takes care of the problem. Any help would be greatly appreciated. Thanks in advance!