95 transport shudder

I have a 95 transport , 200k, 50k on trans.
At about 60-80 K the rpm is very low -1600 rpm & constant shudder is there. I've been told this is most often an engine issue but dont have code reader (yet)- getting one in a week. I was about to do a trans oil & filter with mobile1 synthetic but am hesitant incase it is tranny related?? On the other hand if it is, new filter & oil could address the problem...just dont want to waste the Mobile1- quite expensive...
Is there a common eng problem I should look at? Wires are new...I havent looked at the plugs yet but picked up a new set anyway...
coils? ign module? no enging lite but not all codes show up as eng lite...
Thanks,
Paul

[Wagoon72]

Hi I had a similiar problem with my 95 Transport @ about 190k. Also thought it was transmission related b/c of the symtoms. It ended up being the ignition module, the flat plate the coil pack mount to. Was no spark to two cylinders on the same ignition pack so i initially thought it was the coil pack. After swaping it i found it was the module itself. The shuddering you experience is likely b/c the trans shifts electronically from the tps throttle position sensor and it is shifting to a higher gear even though there is only power from 4 cylinders. Much like you would get in a vehicle with a standard transmission when shifting too early. Anywho that was my prob hopefully your too as a used ign. module is much cheaper than a transmission. Good Luck

Thanks, I'll keep that in mind...I changed tranny fluid anyway & spark plugs...just on the to do list.
I'll let you know what I find...ign mods were a problem on my 93 perodically.
Paul

[yellowfiero]

most likely an ignition issue. May be as simple as wires etc. You will likely get no code from the code reader.