Howdy yall, my 1998 has had a problem for the past 6 months or so (I'm stationed away from home and can only work on it every few months, not being driven while I'm away), that started as a CEL. No problem, pulled out the scanner and saw a P0115 code for the ECT sensor. Wasn't the one on the dash, as the needle would move as it warmed up so figured it has to be the one on the sending signal to the ECM. Replaced it, it fired right up, but still had the CEL for the P0115. Confused I went about rechecked and unplugging then plugging back in the wiring looms I could follow. Now it's back to "new normal" of taking 15 or so seconds to start, then stumbling, and firing up as if nothing was wrong. What's really getting me now is the sound I'm hearing from the bay. Almost sounds like a plunger creating suction every second or so. Link to a video of the sound I'm hearing.

Has anyone experienced this before? I've searched through using the code and long start but can't find any posts (admittedly didn't search too hard) that contain both symptoms. I'm about to throw in the towel and take it to the dealer but know this community has been great and wanted to check with yall first.