I have noticed a slight vibration in my steering wheel and gas peddle as i accelerate right at 40-42 mph. It only happens while its under load. When i coast no vibration. It idles fine and runs smooth. I looked at the pullies and didn't notice anything. the crankshaft pulley has a very little bit of movement. Could it be the driveshaft?

any ideas?

 

Could very well be the driveshaft, check the ujoints ,

 

It sounds like it could use a new set of sprakplugs, I had the same issue, especially at about 40-42mph because thats just about where it shifts into overdrive and is using the most torque when the rpms are just about 1100.