94 Astro late shift from 1-2. Should I panic?

[Funk-O-Meter]

94 Astro conversion van 6 cyl. 104k miles. After market tow package w/ cooler

When I bought it it shifted rough from 1-2. I didn't worry.
Then one day the trans fluid emptied itself all over the engine. I worried.
Turns out it was just a line to the after market trans cooler. I no longer worried.
When I got it back it behaved differently. The rough shift from 1st to 2nd was pretty much gone but.....

Now when I'm starting on a pretty steep incline from stop it seems to accelerate rather slowly and will jerk into second sometimes making the tires bark a little. Only does it from a stop and only on an incline. I can kinda get it to happen to a lesser degree by flooring the accelerator from a stop. Not something I make a habit of doing. Other then that it's actually shifting better then before the cooler line broke. I'm worried.

I can live with it if it's not gonna cause damage. I've got to get it inspected and have the AC worked on so It'll be in the shop soon anyway and I'll ask them to look at it.

Is it serious?

Should I worry?

[CD Smalley]

I wouldn't worry. Check your trans fluid level with the van warm and on a flat level surface... It almost sounds like the trans is starving for fluid when you are on an incline. How much of an incline are we talking here BTW?

[Funk-O-Meter]

Yea I checked the fluid and it seems well. Did it a couple times actually.

I live in the mountains so were talking about a grade of 10 deg plus I think. Though I could be misjudging that. Defiantly a good sized hill you wouldn't enjoy riding your 10 speed up. On milder inclines at traffic lights I tend to get passed by the other cars from a stop. The Van will only accelerate so fast no matter how much I press the accelerator. At some point I can get more RPM by pressing it down but no more speed. It doesn't freewheel but you can hear it. Then it drops into second and I spill my coffee. So I'm just easy on the accelerator.

Should I worry?

[fzskg8]

You may want to look at the mass air flow sensor - if it's dirty, it can have the described effect on shift quality. Cleaners are available at parts stores; most dealers would want to replace it - $250-$350.