I have a 1988 GMC Safari Van-I had the motor mounts replaced due to shaking and loud engine noise when in drive mode and only when break is applied (complete stop). I then had to replace the power steering pump bracket, and engine bracket along with the cerpintine belt. The Van still shakes and increases in sound especially when it is warmed up (driving time aprox. 10min). I do not know what else to check, any help would be appreciated. Pam

 

have your transmission checked out and make sure all of your plugs and wires are good to go.

 

Tough to figure out without actually hearing it. Where does it appear to be coming from?

 

Joe--I'd put money down that miserable thing has the V-6. I had a used 1987 Astro Van v-6 (for 3 months) that had the shakes as well. I hate to say this without examining it, but mine needed a minor tuneup and a Map Sensor.
At work we also use Chevy Astros for couriering and they are the small block V8's and they run great.

 

That is true. It's a V8 with two cylinders cut off.

Original poster: We need more detail to help.