One of my primary injectors wasn't firing. I paid a shop $750 to install a new injector and that didn't fix the problem. They wanted $950 to install a new ECU and I said I'd do it myself, thank you very much. I got an ECU off eBay and installed it this weekend.

It seems to be running better now... but for some reason there's almost no pressure behind the clutch. I checked the clutch fluid reservoir and it's full to where it should be. Obviously I'm going to bleed the clutch. But I looked at the clutch bleeder valve to see what size wrench I would need (looks like 8mm) and I noticed that the dust cap described in the service manual is missing. Could this have let air into the clutch over the few weeks it's been sitting? Should I get a new dust cap when I bleed the clutch?

Background info: 87 N/A 5-speed. E-brake sticks, so it's been sitting in first gear with a brick behind a wheel and the e-brake off.

 

well the dust cap's absence wouldn't put air into th system - if the bleeder was loose it would.

More than likely though the master or slave or both are leaking. Now you may not see actual fluid dripping, it may simply be bypassing the cylinder inside.

Generally speaking, you don't all of a sudden have air in the system - its usually something worn out.