1997 GL Coil Packs

Hi. I'm starting to expereince some shudder at highway speeds that is easily remedied by forcing a downshift. Once downshifted, the van accelerates smoothly and returns to OD on throttle relaxation. I was wondering if this could be a coil pack? If so, how difficult is that to replace? Is it very expensive? This may be the beginnings of a tranny problem but I'm just not sure!

Thanks.

Oh yeah, one more thing! I did the EGR port cleaning several months ago.

Perhaps your problem is caused by the sensor switch that is mounted on top of tranny. It tells the tranny controller what gear you've selected. Its a "DTR sensor" (digital tranmission range), I think.

Also,how long since plugs and wires have been checked/replaced? A bad plug or wire can also cause the concern.

I replaced the DTR sensor a few years ago when the tranny refused to shift into OD. I ended up putting a coil and new plug wires on. I didn't notice the shudder during a 20 minute test drive; however, I also changed the tranny fluid (well 50% of it) and the filter. Thus far, with these two modifications she's shifting very nice.

Thanks!