That seems like a problem I was encountering with my 91 I rebuilt. The ECM was reconditioned by a guy in Florida. Pretty good guys with lifetime warranty on the repair. I never figured out what the problem was but I'm tempted to rule out the ECM. However if you still want to troubleshoot with another ECM, there are a couple of yards in the Denver and Aurora area that always have Monteros. They list the "computer brains" at $30 a pop. Good luck!


'91 RS, '93 SR