Long time, no post. Well, howdy everyone! The fact is that my van has not been giving me trouble for a couple years now, and it's been nice. But around the time I did an oil change last month, three possibly unrelated issues occurred. Whenever I start her up cold, the engine runs rougher than it should, with more shaking and the occasional misfire.
The brake pedal tends to go soft when the engine is idling. This seems to be random, but about 50% of the time at idle.
The lifters are ticking up a storm. When the RPMs are below 2000, it's not bad, but above that they just get noisy: tika-tika-tika!!!

I am mystified by all of this, but perhaps something is causing the valves not to open properly and giving low vacuum at idle to the brake booster and such.
In an attempt to experiment, I poured Seafoam in the gas tank and crankcase, and will do an oil change on Thursday. Maybe the oil filter is clogged?

No check engine light at all.