first option is to have the fault codes read as they will determine the area of the fault
indicates a problem crank or cam shaft position sensor or wiring
Is your check engine light on ? 1990 you can do flash codes ,don't need a scan tool . I'm suprised auto zone didn't tell you . If you look at the DLC under the dash , below the sterring wheel . The top row right , two terminals next to each other , stick a paper clip or piece of wire in both terminals . The check engine light will start to flash . Reading OBD 1 Codes on GM 1982 1995 watch this video !
If u know of someone who has an old scanner u can easily access the codes. Otherwise u need to jump pins a and b in the doc together with the ignition.on but the motor not running. The check engine light will flash codes. Long flashes are r tens and fast flashes r ones. It will start with 12. One long and then 2 fast. This will sequence 3 times and then go on to more codes. Once u have the codes u can look them up to get to the correct failure area. U may still need a pro to diagnosis it further but u will have a clue to the affected failure. Fyi the 12 is just a distributor code that will show up since the engine is not running. This is a normal code and should be ignored.
Can you turn the engine by turning the alternator or water pump ?If the engine turns freely, could be a problem with the cables to the starter or the starter itself.
