So I have a 144 with the b20e and on a cold start it runs pretty decent actually, idles solid, accelerates ok all around pretty decent. After it's warmed up though its idle gets all low and sparatic, its starts back firing on acceleration, and occasionally it stalls out. So I replaced the fuel pump, fuel lines, fuel filter, injectors, air filter, and air filter ducting. And on first start up it sound fantastically solid but after driving for about 20 plus minutes it start going back to it's old ways. I heard it might be an electrical problem

 

I had to deal with a similar issue on my 1972 1800E. It resolved itself after I replaced the fuel tank. Numerous times I tried flushing it because I knew there was corrosion sediment inside of it. I could never cruise more than 20-35 miles before the idle became erratic. On start up it would idle just fine...I could let it sit there on idle for 20-30 minutes with no problem. But as soon as I started driving it for a while the crazy idle started. Just in case you do not have it yet, I attached the B20 FI troubleshooting PDF link.

http://volvo1800pictures.com/documen...lt_tracing.pdf