4kcsq cold run problem

[Smeins, Larry]

My 87 4kcsq has an irritating cold run problem that I am trying to diagnose.
I am looking for basic information on the sensors used to control the
injection system and the control algorithm used.  Is there a site similar to
SJM's that addresses the 4k NA engines?  Or is there a close similarity
between 5k NA injection control and 4k I5 control such that I can use my 5k
Bentley to troubleshoot my recently acquired 4k?  I prefer to understand the
system before going into a random parts replacement frenzy.

The problem occurs shortly after a cold start.  It starts well and idles
well.  If I drive off immediately all seems fine for about 2 city blocks.
At that point something begins to happen that will not allow the engine to
exceed 2000 RPM either loaded or unloaded.  It appears like the fuel is cut
off at 2000 RPM and switches back on when the RPM drops a few hundred below
2000.  If I try to accelerate beyond 2000 the car goes into a severe jerking
state.  With the clutch disengaged and with partial throttle the engine
oscillates between 1800 and 2000 RPM.  If I hold the clutch in and floor the
accelerator the RPM will eventually pass 2000 and once it hits 3000 it
appears to regain fuel and with clutch slipping I can get the car to
accelerate as long as I don't let RPM drop below 3000.  This all lasts for a
mile or two until the engine warms up.  The PO had the car into shops two or
three times to correct the problem.  A water temp sensor and a cracked
vacuum line were replaced along with a complete tune up but the problem
persists.  I suspect some state change in the fuel control system is
switching to an off idle low emissions lean condition, at 2000 RPM, that
should not happen before the engine is fully warmed.  All advice and
suggestions will be considered.

Larry in Loveland CO