EDIT: See a few posts down. Probably I am experiencing something slipping in 4th.

I've noticed that under certain circumstances I can feel a shudder with my 350 TPI. I'm hoping that it's an ignition related issue and not my rebuilt transmission slipping. It is most noticeable after a long drive where I come up to a stoplight at a hill. It goes into lockup (35ish mph, approx 1000-1500 rpm) and I have the pedal fairly far depressed. If I go far enough it will shudder and if I let up it will stop. If I kick it down there is no issue with higher rpm. I don't really notice it shudder under any circumstance other than high-load at low rpm. I don't notice it at WOT, but doesn't mean it's not there.

From this description, does this sound like an ignition issue? I'll be replacing plug wires soon since I'm putting headers on, so I may as well replace plugs as well even though they looked ok. Since the coil and ICMs are problem spots I could check those if the plugs/wires don't fix it.

 

I had this annoying shudder for a while, thought trans was giving up, but was the only had 1 of 3 torque converter bolts in, other bolts fell out, after new bolts, no shudder, just an idea

 

I'll double check that they're all there and tight. I really hope it's not the transmission or the torque converter clutch slipping, as I rebuilt it with a Pro-Built kit a few months ago.

 

I think I can fairly confidently say that something is slipping while in 4th gear. I can't say for sure it doesn't happen in other gears, but something's not right. Today when I was at lockup I let it do the issue while watching the RPM, and the rpm raises with it locked up while it does the slipping and vibration, then goes back down when I let off a bit. So either the TCC is slipping, the 2-4 band is slipping, or (*gasp*) the 3-4 clutch pack is slipping. What is my next move? Anything I should do? I haven't verified pressures yet, but I have made sure it's fully topped off. TV cable is adjusted as well. I rebuilt the trans a few months back with the Pro-Built kit and have an external cooler, but it may still have been getting hot.