That is around town. I also had the crank stroked. The engine that I had rebuilt had had 305 , 54cc heads put on it. I had heard the 305 heads increased the compression. It doesn't make sense someone would do that to a van. We went back to 64cc heads.
I am also wondering if roller lifters would help with fuel economy. If not, if it ain't broke leave it alone.
I also cannot get it to ping, even with low octane fuel. Could that be connected to the shudder.
I know how difficult it is to diagnose from a distance, especially on a forum. I appreciate the feedback. When I have light, I am going to check the vaccum line to the modulator, the EGR lines, and I am going to look for a leak in the advance vaccum line.
Man made it, man can fix it. I will persevere!