Another Trans Problem

I have a 700R4 w/od on my 88 c-1500. The tranny has a litlle over 25,000 miles on it. About a month ago I had a new torque converter put in. Since then, when the truck is cold it has a problem shifting into 2nd and 3rd gear. The tranny place told me that a little dbris could have gotten in the throttle valve and to shut the engine off and put the gas to the floor a few times and it should work ok. It does but I have to do that everytime that I start my truck. I don't know anything about transmissions, I hope one of you does.

Yes that could be the problem,,,,,,if the valve doesn't clear by doing that,,,,the pan should be taken down to see how much JUNK is in the
pan,,,,if some-what clean,,,,the valve can be replaced with a TRANSGO
"cutter" type valve,,,,which is "self-cleaning" works great BUT tranny
has to be in good shape,,,,NOT MAKING METAL !!!!!!
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