Dodge transmission questions

I have a few questions and descriptions of conditions about my automatic transmission I'd like to get answers to, in general terms.
I have a Dodge 3/4 ton B250 van, 318 cu. in. engine. The 3 speed with
overdrive on the column automatic transmission has been rebuilt and 'stiffened/heavy duty parts installed' about 2 years ago by the previous owner. Here's some descriptions and questions.
The trans. is slow to shift upwards in the gearing. Low range really roars, and I have to gently let up on the accelerator to get it to shift up. It then winds up again, usually, and I need to do another but smaller let up of the gas to get it to shift up into Drive. It no longer will go into automatic overdrive, but remains in Drive. That's great for the mountains and hills around here, but still something that isn't working properly. lol Other than the aggravation of having to help it shift, the rest of it is fine, no grabbing, jerking, slipping or any indication of anything wrong, other than the poor upward shifting. It does this harder when cold and easier when warm and run a while, but is still winding out pretty good in the shift from Low to D2 to Drive. I don't have a tach, so don't have any reading of that, other than feel and ear.
Questions: Number one of course is what is the possible problem (problems), number 2 is the possible solution? Third is how expensive will it be. It seems to me that this isn't a transmission problem, in the usual sense of transmission problems, as there is no evidence of gearing damage, etc. just poor shifting. Am I wrong in thinking it's something outside the trans. gearing and bands itself, maybe, such as a regulator, valve or such?
--
HT
.

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It only takes four more digits to include the year. A simple throttle valve cable adjustment might correct your delayed upshifts.
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On Mon, 14 Mar 2005 10:22:25 -0800, "John Kunkel"
evidence of

Geez, sorry, I can't believe I left that out, it's an 89. Thanks
--
HT
.

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