97 geo tracker

replaced ecm & coolant temperature sensor. ran well for 100 miles. car won't idle or shift out of third again. any ideas what may be causing all this to keep going bad?

replaced ecm & coolant temperature sensor. ran well for 100 miles. car won't idle or shift out of third again. any ideas what may be causing all this to keep going bad?If you got a used or rebuilt EMC or from anyplace except at the dealership, you've got another bad one.

get the codes checked first, then go from there. The 96 and up did not have as many problems with the ecm as the 95 and earlier. Is this a 3 or 4sp auto trans. a 3sp not shifting out of third into overdrive sounds like a convertor solenoid, or possible relay. Not idling properly could be quite a few things. See what the codes are and post back