98 volvo d12 low power then no start

Bought a 98 volvo about a week ago to help out another younger driver. Myself and mechanic went threw it ran great found previous owner and had lots of maintenance and repair work done and price was right. First trip out was great until return home. Driver called said there was a loss of power could not go more then 50 mph/85 km coming up the hills would drop drastically he decided to pull off and idled very low 300 rpms then died pulling into a parking spot. Code I have is 144 vehicle speed cruise or peddle. previous owner said that this happened before and caused a no start.

Is the peddle not reading correctly cause a no start?

The truck is about 3 hrs from home my self and mechanic friend who bought the truck with me went to look at it last night 4 hrs later still stumped

All help and advice is greatly appreciated like to get my new driver rolling again he's had a rough month

 

It was plugged in but looked some what newer compared to the truck multimeter was all over the place when turning it with a screw driver and testing it.

 

The t p s tho is a cause of a no start issue tho correct? Have friends that manage a local dealer said if it will solve my issue he will open the store for me today

 

Not sure only had this truck a week and so far it's pretty clean truck but it sat for 3 years bouncing around new owners never getting plated

Thanks for all your help very much appreciated