strange vibration 97 bravada
 

so the motor mounts didn't correct the vibration I've been getting....I have narrowed the symptoms down though...it always occurs at or within 3mph of 50mph...so thats around 1800 rpms in 4th gear, but it also does it at a much higher rpm in 3rd gear but at 50 mph too. it vibrates enough where you can hear change rattle in my cupholders. i can feather the gas at exactly 50 mph and 1800 rpms and keep the vibration going, otherwise it comes and goes as I either accelerate or brake past 50. it also does it if I shift into neutral and coast. it does not do it just sitting still and revving the engine. I'm at a loss on this...please help.

bump for a cure

I'm no expert, but I'll throw in a few tips that help vibration at speeds... but a few questions need to be answered first. :)

Are your tires aligned correctly? Wheels balanced? All tires inflated properly? Does it let off when you turn in a particular direction? (indicating a wheel hub)