gnaples

Howdy, I'm been reading these through these forms and was able to fix some of my other XJ problems, but I finally am making a post because I am stuck on what else to try.

I got a 1998 XJ Sport 4.0L (automatic) last year and I've been haunted by an occasional P0700 engine code and slipping in first gear.
Here's more details:

• When I slow to a stop (stop sign, red light, etc) and then start driving again, the transmission slips and I can only go about 10mph until it finally shifts (several seconds)
• Sometimes while accelerating (usually after awhile of driving) the car will shift, but my RPMs will jump UP when I would expect the RPMS to go down
• After a few instances of either of these, the check engine light kicks on with a P0700 code
• The TPS (Throttle Position Sensor) was reading at 13V +

Here's what I've tried:

• got transmission rebuilt
• new toque converter
• new shift kit
• new solenoid kit
• new input speed sensor
• replaced throttle position sensor (once we realized that didn't fix the voltage issue, we reinstalled the old one)
• new PCM
• Checked and cleaned grounds in engine bay (especially G101)

Anyone have any ideas on where I should start looking next?
I appreciate any and all feedback or suggestions.

gnaples

My mechanic said that there's a likely chance that when they reinstalled my transmission after the rebuild, that they pinched a cable which would've mimicked the PCM issues I was having and explains why replacing the PCM and the TPS did not fix it. They advised me to take it back to the transmission shop. I did and a couple hours later they informed me that they would be getting me an entirely new transmission and it would be covered under my warranty from their previous rebuild. I'm counting on this to resolve my issues.