I have a hot water baseboard, fuel oil heating system with a boiler furnace. The cold water pressure is wonderful (full-force)throughout entire house. The hot water pressure is about 1/4 to 1/3 of the cold water pressure but is scolding hot through entire house. I would like to have same hot water pressure as the cold but with the temperature adjusted. Any ideas?

It sounds like your tempering valve or mixing valve at the tankless coil has see its day, time to relace it , and about the water pressure its reduced at this valve and the pressure drop from your tankless coil itself ,so you don't run out of hot water that's why there's such pressure difference , there are ways to better the pressure you can change the valve to a higher capacity gallons per minute , (gpm) but now you will probably run out of hot water more quick, if you want the good hot water pressure try converting to a oil fired hot water heater , and it will also save you money in the long, and most models are very effiecient, you won't have to keep your heating boiler running all summer to keep that tiny tanklees coil hot , in the long run you will be amazed at the money you save , most residential oil fired hot water heaters fire a fractional gallon nozzle and recover very fast , and if your household uses a lot of hot water this is definitely the way to go, and it's a must if you have a jacuzzi, Anyway at the very least you most likely need a tempering valve element kit , years of hard water deposits flowing through it have taken there toll on it , a new tempering kit should will solve your dangerous scolding water problem, but if its so old and corroded the complete valve will have to be replaced , there is also the remote chance that someone has been tampering with the vave tempering adjustment , if its scolding now you can try to turn the temperature down a bit this will allow more cold water to mix and increase your hot water pressure as a whole , but I have mostly always found that the valve is at fault

Do you have a water heater for your domestic water, or is this a combo boiler?