Project car purchased on ebay. Starts up fine but struggles off the line with the pedal all the way down. Zero power...can't get up a hill. Running it for a while doesn't make a difference. Top speed about 50mph...then engine temp starts to spike until overheat. First indy swapped the fuel distributor from another SL in the shop and that didn't fix it, so he gave up. Then MB of Manhattan said compression on the engine is good but the cat was clogged and engine should come to life with a new exhaust system. They said one of the spark plugs was laying on its side so one cylinder wasn't firing. They re-threaded that so now it sits properly. They suggested I take it to an indy for an exhaust install, which I did. Indy swaps the exhaust and there is no improvement whatsoever. That indy checks the timing which is perfect, swaps in a new fuel filter which makes no difference in performance. I’ve scoured posts and found similar but not quite exact symptoms. Indy is confounded and is about to test the fuel pressure. Any ideas? Accumulator, fuel pump relay, maybe some sensor causing this?