D not running well (but not mine)

["Jim Reeve" <ultra@xxxx>]

Hey folks, today I visited another MN DeLorean owner's place to try 
and see whats wrong with his car.

What its doing...
Starts up right away, but then idles very rough, but will eventually 
smooth out.
Any throttle movement will almost kill the car. There were a few 
times I could get it to about 4500, but usually it wouldn't go past 
1800 no matter how well I played with the throttle.
There seems to be an apparent exhaust leak on the passenger side, most 
likely the manifold gasket, the owner said it wasn't this loud before.

What I checked...
Swapped RPM and LAMBDA relays from my car, no avail.
Removed fuel pump and inspected hoses, all good there.
Did some unplugging and plugging back in of electricals for CPR, Cold 
start valve, frequency valve, and idle motor, everything acted as it 
should.
Idle switch works fine.
Full throttle switch is sticky, but currently unplugged.
Tamper-Proof plug is missing.

My theory...
The owner says this happened very suddenly. He drove it to work one 
afternoon, all was good. When he started it up to go home, this was 
happening. Almost every fuel system and ignition component has been 
replace on the car probably about 1000 miles ago. I suspect that the 
fuel adjustment was never quite tuned proporly (hence no plug of any 
kind on the adjustment hole). I also suspect that the engine could 
have heated up just enough after being shut off, to break some kind of 
seal on the exhaust manifold. With this leak now there, the change in 
backpressure has thrown the fuel adjustment way out of whack.

However...
About a month ago, I was messing around with my exhaust system, and 
ended up with a fairly massive leak at the front seal for the CAT. 
The engine idle and reved fine (just a helluva lot louder) but under 
load, it would shake VERY violently. I somehow cured this buy 
shooting between 30mph and 60mph entirely in 2nd gear 3 times at 
wide-open-throttle, keeping it in gear when coasting back down to 30. 
Now I still had the leak, but the engine was perfectly smooth at all 
throttles at all speeds in every gear. Somehow somthing must have 
compensated. When I got the leak sealed up, there was no change in 
engine operation. It would have been nice to try this in his car, but 
we really couldn't get the D faster than 20mph.

The Questions...
I am suspecting the reason for this is because his fuel adjustment may 
have been out of whack in the first place, but was just good enough so 
the engine would run fine under normal condions. And now that they're 
not normal, it just can't do it. How close am I? Any other 
suggesions? Would you recommend fixing the exhaust leak first, or 
fine-tuning the fuel adjustment?

It seems this post has turned out to be longer than anticipated, but 
at least its detailed! Thanks for any advise.

Jim Reeve
MNDMC - Minnesota DeLorean Club
DMC-6960