Before you go spending tons of money on new sensors and gadgets, remember that the car is basically 20 years old. My 90 was having very similar problems. 1. Buy some electronic parts cleaner and dielectric grease. 2. Disconnect all of your plugs leading to your sensors, especially the black and white 10-pin connectors at the back of the engine compartment. 3. Spray all of the contact points liberally with the electronic parts cleaner and let dry. 4. Fill all of the female contacts with dielectric grease. 5. Plug everything back in. Be careful with the plastic clips, they break pretty easily. This is the cheapest way to fix the problem and should be tried before anything else. At minimum, it will make the car run better when fixed and for longer. Essentially a maintenance item. Good luck and I hope that's all it is on your car too.