Lifter noise, rough cold start, and soft brakes.

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.

Welcome back! Check this hose for cracks or leaks:

http://i8.photobucket.com/albums/a23...s/IMG_2357.jpg

This is where your brake booster robs vacuum from the engine. If this looks okay, then disconnect & temporarily plug the vacuum port. If plugging the port corrects the idle problem, then there's a problem somewhere in the booster vacuum system. There's another rubber hose under the nose of the van (were it transitions from the metal line to the booster), so check that one close too. The vacuum system of the booster can be checked by pulling a vacuum on it. I use a Mity-vac, but you can also do it with your mouth. Just apply vacuum until it maxes out, then hold it for a few seconds. If you find a line or a component that won't hold a vacuum, you've found the problem.

The ticking lifters might be unrelated. Lifter noise can be a sign of low or no oil pressure, so that's the 1st thing to verify. Does your van have an oil pressure gauge or idiot light? If you have an idiot light, turn the key to run but don't start. Verify the oil pressure light (red) is illuminated, then start & verify it goes out. If you have a gauge, then you'll already know what to do. What weight oil are you running? What brand & number oil filter do you use?

Thanks for the ideas,
well, I changed the oil today, putting 10W-30 in with a Toyota filter, as usual. I cut open the old oil filter and there were no visible particles of metal or gunk. Started it back up and the problem is unchanged. To be sure that it wasn't the water pump or alternator bearings I ran it without belts for a few seconds, noise was still there. Oil pressure on the gauge is just fine, and the oil pump is only 6 months old.
I'll test the vacuum hose next, and try unplugging the O2 sensors to see if that changes anything, but now I'm wondering if this could even remotely be a clogged cataylitic converter?
It's just ridiculous that this is happening on a rebuilt engine with 25k miles on it.

Pulling off the valve cover might also shed light on the situation.

I notice the same problem when I start up the engine in the morning. After the engine warms up (3 minutes or so) it goes way. I also notice a low oil pressure when idling that rises to normal when above 1500 rpm. I just bought the van and the oil is a year old ( a little dark but clean). I am hoping that changing the oil/filter tomorrow will remedy. The orange yellow oil light comes on then goes off. I checked the oil level both when warm and cold ( both times they are at the full line). Any other advise?

My lifter noise ended up being a stuck lifter. Not hard to replace, and not expensive, but it was a very distinct tapping from the passenger's side of the engine and with the valve cover off it was shooting oil up.

The soft brakes was a worn out master cylinder, and the rough cold start... well it's not that bad, and I'm putting up with it. Guessing it's Oxygen sensors.