first and easiest thing, free up exhaust and intake. get a cold air intake system (make sure it's california legal). a better flowing exhaust would help, but it wouldn't be a bad idea to get some type of electronic power programmer, there are quite a few out there for gm cars. if you want to get really serious, consider headers, and upgrading the fuel injection system.
What kind of power programmer do you suggest ? I've been told that the factory computer settings are not able to be modified..[ California regs and all ]The fuel injection system is very basic,2 injectors in a carb body..I know this would fly if I could get passed that danged factory computer,or find some way to reset it !!Seems like there is no vacuum advance to it ..Has to do with smog rules and all.The best I can get mileage wise is 16 mpg.Any ideas would be greatly excepted..
check these out http://www.summitracing.com/search/year/1991/Make/GMC/Model/SONOMA/Engine-Size/4-3L-262/Engine-Family/GM-V6/Part-Type/Computer-Chips-Modules/?Ns=Rank|Asc http://www.summitracing.com/parts/TRD-2733/ http://www.summitracing.com/parts/EDL-3713/ i'm not too sure about those throttle body spacers, people say they make some more power but i'm a little skeptical, the intake manifold would do it for sure though, as well as one of those chips, but make sure u get a good tune, get the chip set up right because you don't want to overheat the motor or fry anything. maybe look at a k&n filter at least too
Looking for a Used Sonoma in your area?
CarGurus has 469 nationwide Sonoma listings starting at $2,500.
Search GMC Sonoma Questions
GMC Sonoma Experts