Car:
2009 Mini cooper hatch, automatic, no frills. 76000 miles.
Problem:
Acceleration falters badly, loses power at 2000 rpm (+/- 200). If I just ease on the gas at that point, the forward motion is very 'joggy' and the revs dont go up until my foot passes a threshold and, it eventually downshifts, the revs go up to 3000+ and all is fine, the car accelerates.
This problem is absent when the car is cold, but starts to happen consistently after 5 minutes of driving.
Only twice in the past month has the engine light flashed on, and then it went off right away.
Known issues:
Thermostat housing has been leaking for a month to the tune of half a liter of coolant every 2 weeks or so. I had it changed 6 months ago by a private mech who's no longer around. Just prior to that it leaked profusely.
Battery is very old, still original
Dilemma:
I need to keep the car running safely for a few more months while I take my time looking for a new vehicle to accomodate a growing family. Then I'll trade in.
History:
A month ago I took the mini to a garage to change the VANOS solenoid in order to clear the error code and pass DEQ. He informed me that my Thermostat housing was leaking (again!) and insisted that if I didn't change it, my car would collapse on the road in the next few days. Having just been through a leaky part, I didn't buy his pitch. The acceleration problem has gotten noticable worse since I took the car in. I just changed my air filter, but no help.
Solution:
My thoughts would be to change the fuel filter or maybe clean the injectors, both of which I can do at Jiffy Lube for not too much.
Does this sound like it might help my problem?
Many thanks

 

Sorry for the repost.

 

Sorry to hear of all the drama. When the thermostat housing was changed it would have included a new coolant temp sensor. That’s a plus! The low voltage battery is going to cause a heap of trouble. If it were mine-
1.i would replace battery and get the car scanned properly when the new battery is in.
2. Check hose clamps on everything without engine compartment for splits or leaks. A lot gets moved around when replacing thermostat.
3. Make sure the coolant bottle, cap and hose fitting on bottom are “ snapped in” properly to avoid leaks from there.
4. High octane fuel won’t hurt, but I’d avoid jiffy lube visit above. Nothing good will come of them fussing with your fuel system.
Keep the thread posted and best of luck!!