CIS bogging/missing at 2K under load

[Cory_Langford at bcit.ca (Cory Langford)]

I have a small issue I am stumped on, so I was hoping the combined 
expertise of the list might shed some light on where to look next.

My '78 roc seems to have a bit of an issue when the RPM hits 2K under 
load.

A little history:

It has been sitting waiting to be dismantled for about a year and a half. 
(long story but I decided the rot was too much to fix, changed my mind 
now).

So I pulled it into the garage, gave it a fresh oil change, new plugs, 
rotor cap, wire set and it seemed good to go.  Had a few idling issues and 
other electrical issues and ended up replacing the alt. and that solved 
the problem. (had only about 10V to the coil and the car did not like 
that)

BUT, here is the current issue.  Idles great now.  Runs well at all RPM 
ranges except 2K loaded.  If I am running on a nice flat road, or going 
down a hill, etc and there is no real load on the engine, the 2K area 
actually runs okay.  If I load it up (ie: up the hill, accel, etc) when I 
hit the 2K mark the engine runs rough and will miss occasionally.  once I 
hit 2500 everything quiets down and it runs real nice again.

It is running to lean at the 2K mark and this is what I believe is causing 
the problem. I just can't figure out how it can get starved for fuel at 
only 2K and be okay above that (or how to start remedying that situation). 
The o2 sensor I installed in the downpipe shows it running very lean at 2K 
(.15-.25V), running perfect at idle (.44-.47 Volts), just into the lean 
around 2500+ (.35-.4 V) and a little rich under boost (.6-.65V).

Just to throw a wrench into the mix, it has been turbo charged.  The turbo 
is very large for this engine, so does not spool until about 3K.  So it is 
not the turbo that is adding the extra air (I think).  I am not sure how 
much vac. a 1.8 8V engine normally draws under load, but when loaded at 2K 
I am currently reading 10psi vac.  Boost sets in at about 3K with roughly 
2psi at that point.  It seems to idle at about 16-18 psi of vac. at the 
moment.

I thought I had a small lean in the intake area, so I changed the injector 
seals and it seems to have disappeared.  But the problem is still there.

Any suggestions?

Cory Langford
'86 Roc turbo, 
'78 Roc turbo - Daily driver project,
'65 Ghia Coupe
95 Eurovan, etc, etc... :)