Well the car is a 90, which get a ASM dyno test. If they still do it the same, put the sniffer in the exhaust and hook the clamp on the plug wire.... Basically the car just needs to be in good (clean) running order. These test are all based on the numbers from the gas sniffer, make sure you have a good 02 sensor (this is where the odb2 stuff might hurt using the obd1 ecu) is one of the most important things. Other things are egr valves, pcv valves, plugs/wires, basic tune up stuff.