300sdl injector pump

[kenwc21]

Hello folks here I am again.
My 86 300sdl

2 weeks ago, the hard line from the injector pump broke at the pump (#1 line). I took it to my mechanic and was replaced. 1 week later the #3 hard line broke, at the pump, had it replaced. Afet noticing diesel fuel leaking on top of the pump, we replaced all the O'rings in the pump.

Now the car runs horrible. At idle, it shakes, alot, and doesn't stop until you reach 2,000 rpm's then everything seems fine. Back again to idle it's real shakey and continues until you reach 2000rpm's. Funny, but it ran fine even when the IP was leaking.

Took it back to my mechanic, who disassembled and checked all the O'rings to see if something had fallen in during O'ring replacement. Nope, not that. Then he checked fuel delivery from the injector pump, and #4 was not delivering any fuel.

In all your opinions, hopefully someone will have the miracle answer. Does it sound like I need a new IP?

As always your feedback and help is grealty appreciated.