98 sierra 5.0 hesitation problems

[98sierraman]

I have a 1998 GMC Sierra with a 5.0. liter engine. The engine has 118,000 miles on it. My engine idles fine, however when I give it gas it seems to hesitate, bog down, and occassionally misfire. The codes that came up indicated low voltage from my o2 sensors, and misfiring. Since the problem first started I have changed my O2 sensors, plugs, dis cap and rotor, fuel filter,and cleaned my fuel injectors. I also had a fuel pressure test and vacume test done on it, and the mechanic said that everything was normal. Some days it runs better than others, but it still has the same problems. This has been going on for two months now and Im getting really tired of it!

[Chubes]

I had the same sort of problem with my wife's 93 S10. It idled fine and if I really took it easy it was ok, but the second I put my foot into it it ran like crap. The codes it gave me were throttle position, manifold absolute pressure and idle air control sensors. I replaced each one and the thing still ran like garbage. I finally took it in to the Chevy dealership and it turned out to be the temperature sensor. The computer thought it was running at 15 degrees celcius even when it was at normal operating temp. It was choking the engine out like crazy. I spent $18 on the new sensor, they gave me a bunch or re-call sensors for free and after installing them the thing never ran better. So after spending $350 on the first 3 sensors (which I couldn't return becuase they had been installed) all I needed was an $18 part.

[98sierraman]

Thankyou for the info, I will try that next! Sounds almost identical