OldTL

Hi I have a 1997 TL 3.2 with a surging idle problem. I had replaced the cat and o2 sensor recently and also the battery. It then threw a code for ECT and within a few days started mildly surging at idle which I thought was air in the coolant system (I've had that problem many times). i changed the ECT sensor and it stopped throwing the code but immediately starting surging badly at idle and low rpm driving. I burped the coolant and nothing changed. After a few days it threw a code for MAP sensor high input so I changed that. Again nothing got better and still is throwing MAP code. I unplugged the map sensor and it runs great in limp mode. I'm thinking maybe cleaning the idle valve or changing it. I would think if it was just dirty it would not run great in limp mode though and if it had bad electronics it would probably throw a code. I'm not sure where to go next.. Also I'm wondering if the o2 sensor is defective as it run fine before I changed the cat/o2. Also the battery cables need to be jiggled occasionally or not enough power comes through to start the car. Possibly corroded cables? Also it runs extremely rich right now and surges mildly on the expressway and a few minutes later will lag back down again. Also the engine has a noticeable shake to it now. Thanks!

OldTL

Update:
After wasting a hundred bucks on a new MAP sensor I fixed the problem. I checked for vacuum leaks and found that one of the hoses going to the iacv had a huge tear in it and was leaking massively. I pulled the cable to the valve which lowered the rpms to near nothing, then plugged it back in. It was idling really low and weirdly so I restarted the car and suddenly it ran almost perfectly. No shake or surge. I drove it around and got it to surge very mildly a few times at stop lights. Put a new hose on and no more surge, not running rich, and absolutely no shake at idle anymore. It's had a very tiny shake to it for years so I'm guessing the hose has been leaking for a long time but got worse recently.