[R. Aster]

Hi guys, a little expertise if you don't mind. On my almost 100% stock 89 3.2 Targa (41k miles), I get these symptoms:

Very jerky motion (like a horizontal yo-yo) sometimes on decel (say, in 2nd) with foot off throttle from 4k down to 1500
Seems a little worse when air and engine are cool / cold
Worse when the AC is on
Some popping
A little jerky at low RPM constant speed, but drivable
Very occasionally hunts at idle from normal 900 up to 2000
Accelerates very well and runs well at cruising speed

More data:

If I pop off the oil cap to force it a little leaner, it seems to help somewhat.
It does do it from complete cold start, so does that mean it can't be the O2 sensor on an 89?
This car was just chipped (SW standard), but it did it somewhat before. Perhaps a little worse now.
Feels like something in the drive train has got some slack, contributing to the yo-yo. What would that be, guys?
Maintenance has been kind of desultory on this car, which I would like to blaim on the PO, umm, except I am the OO... Have not had the 30k maint done yet, so IIRC rotor, cap, plugs, wires, are original. Oil and air filts have been changed regularly.

Based on reading here, I'd guess it's running a little rich and the drive train slack is emphasizing the problem, so,

- Does that sound right?
- What would need R&R in the drive train?
- I read my Bentley's and comments here, but still not clear if there is any mixture adjustment that the DME won't just override
- I should check the head temp sensor, right?

I don't mind a shop trip but have not been very delighted with the dealer or the couple local shops I tried. If someone's got a good shop in MD near DC, I'm all ears.

Thanks.

RA