I believe you should have a two pin connector under the dash on the passenger side (the 90-93 model does and yours should too). It is just above the kick panel. You can short out that connector with a paper clip and turn the ignition to on (not run). Then the computer will flash the codes to you. Short duration flashes are a single digit code; long are a second digit. I.E., three quick flashes is a code 3, Two long flashes and 1 short would be a 21. Multiple codes are separated by a long pause in between. The MAP sensor is a manifold absolute pressure sensor that determines the manifold pressure and converts it into an electircal signal for the computer. It could have a vacuum leak and cause idle problems. The Map sensor should give you either a code 3 or 5.