I have a 1991 pontiac trans sport with a cold start engine surge. At cold start up the engine will increase and decrease in the rpm and sometime die but ofter the van worms up it seems to run ok.

Pontiac Trans Sport Wiring Diagram and Electrical System ...

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Aug 28, 2010 - The following link provides detail information regarding the 1993 Pontiac Trans Sport Wiring Diagram and Electrical System Schematic. Herein ...

#? Pontiac Trans Sport Wiring Diagram and Electrical ...

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The following link provides detail information regarding the 1993 Pontiac Trans Sport Wiring Diagram and Electrical System Schematic. Pontiac Trans Sport ...

Pontiac Trans Sport Repair Manual, Service Manual Online ...

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is it efi engine or carburator ......you may nedd to clean intake throttle body......

cold engine idle surge. (problem)
RPM range of surge not stated
300-700 or 800 to 1500? (range is critical to diagnosis)

bad fuel
running summer fuel in winter (running old fuel?)
needs a tune up bad, see the list in the operator guide.
idle speed controller,sticking or EGR valve same. (clean them)
location not stated, so cant guess about local air temps.?
no other symptoms, lack of engine power? etc?
was it ok last week, or better, when was the last time it was OK?
1week, 1year?
surge , causes, on a tuned engine might be:
1: too lean. so lean the ISC can not control idle. rpm low, stalling
2: too rich, flooding, stalling, spark plugs foul (look at them)
3: weak compression in 1 or more cylinders.
4: bad spark.
5: air leaks, in the plenum causing , ISC to lose control.
why high RPM?

especially?
well that means it fails hot too.
and there is a simple tests. for hot surge.
is engine fully hot? 180F and holds solid there?
say rpm is about 800
and you turn on head lights, heater fan and (not AC) and defrost.
the RPM must hold or the ISC is failing.
ISC -= idle speed controls. (all EFI has this function)

check the fuel pressure, you may need to change your fuel pump.

Replace crank sensor. Just above oil pan between engine and transmission.

If it only warms up to operating temperature and dies check the EGR Valve. It should be open within 10 minutes or so. If not the engine will die out although it will start after the engine cools down again

fluid level could be low,if its ok then rip this lazy mans gearbox out and fit a manual ,think of the fuel economy and YOU will be in control

Does your van have the V-Tec engine? If it does, you will have to take it to a dealer to get it fixed. What is happening is one or more of the solenoids under the valve cover is malfunctioning. The result is the surge in rpm's and the rough transition. You could try an indy mechanic but any mech worth his salt will tell you to take it to the dealer.

if the static speed increases and decreases with engine speed, possible bad engine ground or perhaps cheap spark plug wires, or something related

Check ECM control unit???