I need the vacuum line diagram for a 1999 GMC SONOMA 2.2 5 speed

Depends on what vacuum lines google it select show images or auto zone has diagrams on line

go to this link you might find it there... brake line diagram for 1998 Sonoma gmc highrider Google Search

Look on the cross member in the front of the radiator on the driver side and there should be a drawing there. Hope this helps.

Fig. 31: Engine vacuum schematic-1996-99 4.3L engines (click over pic for zoom)

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Possible failed fuel injector if the code is for one cylinder only. Multiple cylinder misfires can be caused by low fuel press. Another possibility is a vacuum leak at intake runners.

2002 GMC Truck Sonoma V6-4.3L

2.2 engine as your standing in front of the engine is all the way back against the fire wall on the left side under a steel plate that has 3 bolts holding it on. The one on the back of the head you can loosen and not take out.
Is there any fuel in the vacuum line going to the regulator? Will the vacuum line hold vacuum? If your answer is no and yes your regulator is ok.

GMC S10/S15/Sonoma Pick-Ups 1982-1993 Repair Manual
VACUUM DIAGRAMS (See Figures 1 through 85)

Below is a listing of vacuum diagrams for most of the engine and emissions package combinations covered by this manual. Because vacuum circuits will vary based on various engine and vehicle options, always refer first to the vehicle emission control information label, if present. Should the label be missing, or should vehicle be equipped with a different engine from the car's original equipment, refer to the diagrams below for the same or similar configuration.
Check the link autozone.com (free register), select the year ('91 sample), Brand, Model, Sub-Model, Engine Size and make the next root...
1991 GMC TRUCK S15 4WD 4.3L TBI 6CYL REPAIR GUIDE >> EMISSION CONTROLS >> VACUUM DIAGRAMS

I really hope helps with this (remember rated this help). Good luck.

it sounds like the fan speed switch ...but im no expert