Any advice for my wife's '96 T&C Chrysler Minivan that is doing strange things after replacing blown 3.3L engine with lower millage engine:
Background:
1) My mechanic is competent and have used him for years;2) 3.3L engine blew at 135,000 miles and asked my mechinic to find/replace the 3.3L engine;
3) After much time, found 65,000 mile engine and I said to go with it since it took so long to find this one;4) Engine seems to work very well, even better than original;
5) First strange thing that showed up in first 200 miles was that the front windshield wipers would cycle one time only by itself. I can add that the T&C did do this when new and it took dealer three tries to fix which they said it was a bad series of 6-way switch on column;6) Second strange thing was that the transaxle downshifts by it self. This is much more serious and also showed up in first 100-300 miles after reinstallation of low mileage engine;
7) Tried adding "Lucas Transmission Fix" product since the minivan was laid up for about three months and both my mechanic and I thought it might be the inactivity causing problems with fairly high mileage transaxle. However, Lucas didn't help and still have downshifting problem;8) My big concern is that I have had one downshift on highway doing about 60 MPH and RPMs jumped from normal 2300 to 5000. I pulled over quickly, turned engine off and on again, and was off again with no more incidents on that specific trip;
9) Check engine light has not come on yet, but mechanic wants to see if any codes show up, which I'm trying to get done today; and10) Another observation: problems occur 50-70% of time when hitting bump which is causing my mechanic and I to think it might be intermittent electrical connection in one of the engine connectors.
Any advice (keep it clean and constructive, please) would be appreaciated.
Bob