2003 montan slow upshifts after battery disconnect

Hello All,

I went through the intake manifold replacement fiasco this past weekend on my 2003 Montana. Along with the gasket repair, I replaced the spark plugs. The job is complete but I have 2 problems.

The first and primary problem is that the transmission is slow to upshift since the repair. It's noticeable on all upshifts, but most notably on the 1-2, 2,3 shift. I had the battery disconnected for the duration of the project but did not make any changes that should have affected the operation of the transmission that I'm aware of. Any ideas?

Secondly, there is a small solenoid with a vacuum line attached to it between the throttle body and the EGR solenoid. It has an electrical connector and a vacuum line that goes to a tee right behind the throttle body. I see an open port on this solenoid that pulses air when the engine is running but cannot find a hose to connect to it (and don't remember removing a hose). Any ideas what this is or if it should just be capped?

I have no CEL or warning lights. The van seems to run fine with no loss in power or hard starting etc. Seems like the repair went really well but the transmission thing scares me a little bit.

Thanks in advance.

Sure wish there was a reply to this question. I just got my 2001 Montana back from a "reputable" shop; had intake gaskets replaced, as well as intake gaskets, spark plugs and wires, etc.
Same problem - slow upshifts. They had not disconnected the battery, so that's not it. But they were completely sloppy in making final wire and other connections. Loose band clamps, mis-routed wiring, mis-routed hood release cable, and the kicker: a loose big red wire atop the alternator. That's a whole different fiasco late last night.
Anyway, because of the sudden appearance of the slow upshifts, which I am sure is because of something the shop did, I strongly suspect a missing or loose electrical or vacuum connection somewhere. My research so far this morning indicates a likely vacuum leak someplace.
Any help, anybody?

I ended up finding the line that went back to the charcoal canister and hooking it back up to the canister purge solenoid.

I drove the van for a week after I had been told that the computer needed time to retrain the transmission. Zero change. So I power cycled the batter again and it's been fine ever since. Try disconnecting the battery for a while and see if it improves.

I could not find these things: the charcoal canister and hooking it back up to the canister purge solenoid. Can you tell me where they are located? Not underhood, unless way down low inside a fender, where I didn't look.

A lot of online research later, I was only finding info pertaining to a failure of unknown origin. My problem is 99% likely caused by the shop who did the head gasket repairs.
So after posting here, I got the advice to reset the computer again. I did so, pulling the positive battery cable off, yanking battery and ECM fuses, then pressing the horn and brake pedal to ensure the system was drained. I also double-checked every vacuum and electrical connection I could see and reach.
After about twenty minutes I put the battery cable back on. Strangely, my radio settings had been retained. I found that after the shop repairs, too, but maybe they had pulled battery power after all (which does make sense).
Finally, I took the van on a couple of twenty mile drives, both around the city and on the highway. Result: the transmission is shifting normally. I cannot explain it, and so am not completely convinced that the problem is resolved.