2000 astro pulsates at 60mph and over ??

[CHEVY1]

Hello

I have a 2000 chevy astro. at city speeds it drives very well, but when on freeway and reach 60 plus mph i feel the van like pulsate or hesitate , but not engine wise because if i have to punch it to pass there is no motor hesitation. I know i have an issue with right rear axle as this sight advised me of a bulletin to have gear lube changed and i did , but the vehicle has just been doing this like the last 4-5 months and not prior to. i had gear lube changed 2 years ago ( and axle still skips in turns etc not as nbad) don't know what to do there or if this is effecting the van in this over 60 issue. I have been told maybe a fuel filter???. about 3 weeks ago i have had van after sitting for 2 days in gararge miss fire and then go away after a short run also. my last complete tune-up was about 2 years ago. Van always starts nice and idles well. I am thinking fuel filter or drive train? any help would be greatly appreciated. I have 132,000 miles on it and it will be towing season here in a month. I also had tranny flushed about 6 months ago.. humm now could this have anything to do with? shifts just fine though...... thanks for your time

CHEVY1

[dewaynep]

Sounds like it's time for a good ol' cap and rotor tuneup. Be sure to get AC/delco cap AND rotor only.

[old_master]

A new set of AC Delco #41-993 plugs with a gap of .060" and a set of plug wires might be a good idea too!

[gelcol]

or egr needs to be clean.