My 89 wagon had these symptoms last summer. Per the advice of the brickboard I focused on the fuel pump relay, first resoldering it and then replacing it. It didn't help. I checked the 700-900 FAQ and decided the problem sounded more like a dead RPM sensor. (BTW, I had also checked the AMM by disconnecting it: the car runs rough without it but when I plugged it back in the car was fine-so I eliminated it. You can find them for an 89 for about 275.) The RPM sensor for the 89 is on the bell housing held in plaace by 1 10mm bolt. Needed three extensions (6",6", and 3") on the ratchet to reach down in there but had the part replaced in an easy, greasy, half hour. Presto! Car runs like new. The sensor is ~50 bux from the dealer. One other thing: this malfunction will throw up failure codes on the onboard diagnostic computer that may indicate a bad AMM but you have to look at all the symptoms and decide for yourself if the AMM is bad or something else is acting up. I was ready to replace the AMM when I decided to make one more attempt and try this.