Oh. The miss is gone. Seafoamed the car and it went away.

 

it may b a small vac leak listen for hissing on top of ur motor those vac lines rot and crack pretty easy if not that def timing

 

as for the vibration in 5th, i've had an issue too. my only suggestion is to check the harmonic balancer for wobble, u-joints and even transmission mounts to see if those are fine. any and all could cause terrible shaking/vibration while driving at a certain RPM.

 

Had timing professionalaly done. It's fine. Also changed all vac lines with new. Still vibrates like hell. Harmonic balancer is new along with the transmisssion mount. On the original 87 universal joints though. See if changing those fixes it.

 

Can't hurt to change the u-joints but if its u-joints causing the vibration it would be more relative to driveshaft rpm And vehicle speed, not gear relative. The fact that adjusting the timing back changed the rpm that the vibration occurred leads me to believe its more of an internal engine or trans issue. Just my $.02