M20 Weak spark, misfire on cyl 5 only

[schlafr]

So all plugs are fouled?? First you'll need to ensure your TPS is adjusted correctly, test your ecu temp sensor isnt faulty, ensure your ignition timing, gaps and spark plug heat range is correct.

Low fuel pressure could cause the fouling, does it buck and surge when you put your boot into it? Drop power around RH Corners?

I think your getting onto something, haven’t adjusted TPS but I don’t know why that would ultimately cause 1 cyl misfire, haven’t tested temp sensor nor heat range, I think I’m getting low fuel pressure due to a clogged fpr, haven’t had it running on the street yet but yes it bogs/stalls when I give it a blip of gas then returns to idle, only revs if I slowly push the throttle, no blips or stall.

[bangn]

TPS needs to be adjusted correctly so its on the right fuel map. ie.. not at WOT when at idle. Pretty common on these cars to be full of oil and muck.

If your fueling is off and you have fouled plugs then its likely pulling leads will show no difference as tested. Needs the right mix of air and fuel. Also to note fouled plugs will not clear themselves up and will need cleaning up to continue testing.
I trust you can hear the spark jumping when you pull and push the lead back on? I assume this is the distributor type on the LH side of the block?

How hard is the fuel hose FEED to the rail (not the one exiting the fpr) at prime and during engine operation, it should be pretty rock hard so long as your hose isnt old as hell. If its squishy then I think somethings up with your lift pump. If it takes a while to crank over that's another nail in the coffin