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Bogging down/hesitation

My '92 100S, with V-6, has recently been bogging down (like a bad case of turbo lag... in a car without a turbo!!), mostly after startup, while the car is cold, at low rpms (i.e. once the automatic shifts into second, it bogs down). It also does it when it is warm, but not as badly. At that time, it just shows up mostly as sluggishness. I really have to step on the gas to get any decent performance, and then... it still feels like it is being held back.

At 121,000 miles, I have never had my OXY sensors replaced. Should they be replaced by this time? Any other possibilities?

I few weeks ago, I put on a Monza exhaust that lowered the backpressure a bit. Would this have any impact? The car had been running fine for a week or two, and then just recently (especially during and after the QCUSAS LimeRock event), it has been plagued with this problem. I don't think it is the exhaust... since I seemed to have aggravated the condition (or caused it?) at the track.

The car seemed a big sluggish before I went on the track (but with no hesitation/bogging down), and while on the track, it got really sluggish at high rpms (i.e. above 4000 rpms... in automatic 3rd gear... on its way up to 5000 rpms...), and wouldn't rev the way I wanted it to (i.e. no wonder why I couldn't break 100 mph on the straight!!). Instead, it would downshift into 2nd (yikes!!), and hit redline, and then go back down to the 4000 rpm range. At one point, the car was idling rough (and now occasionally does... otherwise it starts and idles perfectly), and I thought it was going to stall (right as I was pulling into pit lane, to go out on one of my sessions).

So, any thoughts? Are my OXY sensors finally "fried"? Anything else for me to check first? Fuel pump? Clogged "cat"? Vacuum leaks? Throttle position sensor? Manifold sensors etc...?

If it is the OXY sensors (argggh... there are two on the V-6), does anyone know the best place to get them cheap (I believe they are the 3-wire ones...)? Are they fairly easy to install on a V-6? Anyone BTDT?

Thanks in advance.

Jim Griffin
Maryland, USA
"Perception is often stronger than reality!"
'92 100S