Total newb here. I just picked up a '92 Dakota 2wd, 5.2 litre, auto trans, 200,000 km truck. I have always wanted one and was very happy to find one in my neighbourhood that's been parked since 2007. Even the A/C still works!

Short story is: after tune up (found one bad plug) I still have a shudder starting at about 1500 RPM continuing up to, but lessening in severity at about 4000 rpm (that's as high as I took it). Overdrive works fine, as does the OD off switch. The transmission shifts fine (after I topped up the transmission fluid) except for this shudder. No miss or shudder when engine is revved in park. Shudder seems to be rpm specific rather than speed specific and is worse under load or going up hill. All u-joints and centre bearing are nice and tight, but appear original.

Trans was rebuilt/replaced by previous owner when he pulled a fifth wheel RV without a trans cooler.

After reading the Allpar articles recommended in FAQ#1 I thinking that this could be due to old/incorrect transmission fluid vs the required ATF IV.

Question is: Could this really be just a fluid problem? It seems kind of extreme behaviour for just fluid.

Any insights or feedback are appreciated.

Thanks