1998 Yukon Stumbles/hesitates under load

[DonYukon]

as per the description, just started today

-1998 GMC Yukon
-Stockish 5.7 vortec (black bear tune and shorty headers)
-Mileage 230k

So in neutral/park truck revs nice through RPMs
Put it in gear no noticible bog or missfire no CEL but on take off truck wants to "bog and stumble" The truck has been sitting over the last year more often maybe racked up 500 miles in a years time (offroad toy)

So no CEL and on first inspection fluids are good minus the gas unsure about it has not had a fill up in almost a year maybe bad gas? but I do put 89 octane in it since that's what my tune is for
haven't pulled them but all vacuum hoses are connected ,

anybody know where to start that's really common? I cant find the threads but i remember reading people saying could be a faulty TPS? Just trying to get an idea on where to look first without throwing parts at it or testing everything

thanks in advance

 

[HotWheelsBurban]

as per the description, just started today

-1998 GMC Yukon
-Stockish 5.7 vortec (black bear tune and shorty headers)
-Mileage 230k

So in neutral/park truck revs nice through RPMs
Put it in gear no noticible bog or missfire no CEL but on take off truck wants to "bog and stumble" The truck has been sitting over the last year more often maybe racked up 500 miles in a years time (offroad toy)

So no CEL and on first inspection fluids are good minus the gas unsure about it has not had a fill up in almost a year maybe bad gas? but I do put 89 octane in it since that's what my tune is for
haven't pulled them but all vacuum hoses are connected ,

anybody know where to start that's really common? I cant find the threads but i remember reading people saying could be a faulty TPS? Just trying to get an idea on where to look first without throwing parts at it or testing everything

thanks in advance

When the TPS was bad on my Burb, it would fluctuate at idle, w/o even being put into gear. When I pulled the old original one off, the pin thingy on it was really loose, and the new one was tight. I don't think they're too expensive, but you could check that out( if the pin is loose). If it is, may be the problem?

 

[DonYukon]

When the TPS was bad on my Burb, it would fluctuate at idle, w/o even being put into gear. When I pulled the old original one off, the pin thingy on it was really loose, and the new one was tight. I don't think they're too expensive, but you could check that out( if the pin is loose). If it is, may be the problem?

Ill look at that tom afternoon. Im also considering looking at the MAF sensor but then again most of these sensors should throw a code... its also completly possible my CEL light is burnt out Illhook up the scanner tom and see whats up

 

[HotWheelsBurban]

Sounds good! On my Burb, the TPS and IACV were both original ( this was in 2019 so they were 20 years old). I did TPS first, and then a week or so later I replaced the idle air control valve. Many times,they go out at about the same time,or one will take the other one out.

 

[stutaeng]

Do you have some sort of scanner that gives live data?

Fuel pressure gauge? Is your fuel pressure staying acceptable when it stumbles? Best way is to get a guage with a long hose and stick it to your windshield with duct (duck?) tape.

Fuel trims are your friend here...