Car has running issues

[pontiacgp]

If the EGR is not opening at cruise you would not notice anything, if you floor it then your valve might ping caused by the increase temperature of the combustion chamber since the EGR is not allowing the burnt exhaust to cool down the combustion chamber. If the EGR is stuck open your will have a rough idle. When the engine is cool you can put your finger under the EGR and push the valve open to see if it is stuck.

For the cam timing I'm saying if the chain is stretched the effect will not change with RPM.

For the accelerator pump it's easy to check with the air cleaner removed. As you go to WOT there should be gas being sprayed into the carb consistently.

Have your checked the in and out temperature of your catalytic converter to see if it is plugged and affecting the car's performance. That could be coming apart inside and rattling

 

[oldscutlasswagon]

The car is '82. Thanks for the vacuum specs. I would like to reiterate that WOT is the only time the car doesn't hesitate, but there is no rough idle. I feel this eliminates accelerator pump.
The EGR moves by hand. I have little experience with egr's but I did make sure the engine shut off when I manually actuated the egr. I now realize I should have started the engine and tested it by moving the throttle and seeing what happens. I will do this.
I had a new muffler installed and asked the shop to start the engine and blow out the exhaust a little (not that this is conclusive). If I am correct a backpressure will show up in the vacuum test as low vacuum (correct?). The rattle sound is definitely coming from under hood.

 

[pontiacgp]

Have you checked the timing with a timing gun yet or looked down the carb to check the accelerator pump through it's full cycle?

 

[oldscutlasswagon]

Having no manual I need to know which plug wire (# and position) to read from and what base and total should be. I procrastinated prepping for Xmas this year and my days have been spent frantically going around town, you understand I'm sure.

 

[Texas82GP]

 

[pontiacgp]

first thing you want to do is to get a white paint pen and mark the 0 in your harmonic balancer cause if you don't you'll never see it. You use #1 plug wire for your tinning gun. You should have a sticker that has the timing degree but if you son't I'm pretty sure the base timing for your engine is 16° BTC and check that with your vacuum advance unplugged and plug the vacuum line so there is no vacuum leaks.

 

[Texas82GP]

https://gbodyforum.com/threads/how-to-set-timing-on-81-buick-3-8-n-a.45221/
The timing spec should be on the decal on the fan shroud but based on the thread linked above, it looks like the timing should be 15° advanced.

 

[oldscutlasswagon]

Ok I will do some testing as soon as possible. Thanks, will keep thread alive.

 

[oldscutlasswagon]

Good update: After Xmas ended I finally had a second to look at the car. I plugged the vacuum line to the egr, let the car warm up, and took it for a freeway drive. The cruising hesitation was pretty much gone to the point I feel comfortable driving the car again. To me this verifies the egr caused the cruising hesitation problem.
The only other 'issue' with the car that remains at this point is the slight hesitation off idle. This one isn't a big deal, but I will keep poking around to try and figure it out too. Appreciate ya'll

 

[pontiacgp]

did you have the EGR hooked up to a ported or manifold vacuum?