90 v6 auto sputtering on highway

[90slug]

Just did a FULL tuneup on her. plugs wires fuel filter air filter cap rotor etc. still bucking/ sputtering over 60 mph. drives fantastic around town, only at speed above 60 does it do it. seems like its speed related not rpm related (2500 rpm around town is great, but 2500 on highway is buck city!) any ideas? Ive checked the throttle body which looks very clean! also ran lucas through the fuel system. Maybe seafoaming will help?

 

[vandert]

Had the same issue, had to adjust the TPS - see 4Crawler for Allen head setup, and then ran Seafoam, after that it needed and o2 sensor, between those three things it went away, did you install the fuel filter in the correct direction, sounds silly, But, it has happened

 

[90slug]

haha it does sound silly but I checked to be sure lol yeah gonna try some seafoam tomorrow and possibly adjust the tps. It was running fine until last week, which prompted the tuneup.

 

[Joehert]

I think I might have the same issue. By "sputtering", do you mean it shakes a little at that speed?