hey, I have a 97 Dodge 1500 and a 87 W150. I love my trucks but my 97 seams to have alot of problems. Oil sending unit leaking to rear main seal leaking. My question is my 97 i seam to lose vac. when a go above 2500 rpms. I lose cruise control andthe hvac goes nuts. when I let off the gas every thing is normal again, well close to it.

 

You've got a vacuum leak somewhere. A popular place to look first is the check valves.

 

I have been looking but I just don't see a vac leak. Is there a easy way to look for a vac leak. I have seen a guy smoke check a grand national one time.