MR2s from the year 86 are better. Some exterior and interior changes were made, but the transmission was changed from old C50 to newer C52. C50 had some problems with 5th gear in ages.
But the best would be 89 model. It had everything solved from the early models. 3rd brake light was moved to the rear spoiler.
Engines were great but i would go for 1,6 liter 130HP, 4A-GE. There is a more powerful 1,6 145HP, 4A-GZE, but it was supercharged and there are really a few good pieces.
But overall go for the models 88 and 89. Also try to look for second generation, it is better looking, more powerfull and better on the road