I have a '90 Nissan Maxima , and a year ago you barely even heard that the engine was even on! But things changed now, I accelerate to 2,000 rpm (the #2) and the car barely inches until It shifts to second gear, where everything goes fine from there...

those are notorious for worn out transmissions, have that checked first. if so, remove one quart flluid , put in a quart of lucas tranny additive, and pray. Cause a rebuild on that tranny is 5 times the value of the car