Another m20 rough idle problem--i know i know..plz read

[Mthrizzle]

BORED HERE AT WORK SO I THOUGHT I'D "ASK" YOU GUYS FOR SOME HELP SINCE I HAVE EXHAUSTED EVERY SINGLE OPTION EXCEPT FOR 2..
I RECENTLY DID A 327 SWAP, I.E 2.7 BOTTOM END WITH 2,5 HEAD INTAKE ETC..BLAH BLAH BLAH..
WHAT WAS DONE TO ENGINE - ( SUPER ETA)
1. I HEAD, INTAKE, 272 REGRIND CAM, HEAD GASKET TIMING BELT WATER PUMP ETC.
2. MILLER MAF AND CHIP WITH MUSTANG INJECTORS

THE CAR STARTS AND RUNS BUT HAS A VERY ROUGH IDLE WHEN WARM AS THE TEMP GETS HOTTER THE ROUGH IDLE INCREASES.

CHECKED FOR COMPRESSION - GOOD
CHECKED FOR SPARK - GOOD
CHECK FOR FUEL PRESSURE -GOOD
CHECKED ECU ( 3 DIFFERENT ONES ) SAME ISSUE

I HAVE ISOLATED THE ISSUE TO A DEAD CYLINDER ON # 5

WHAT I HAVE LEFT TO DO IS
1. CHECK VALVE CLEARANCE
2. LEAK DOWN TEST

MY QUESTION IS THIS..WHAT COULD POSSIBLY CAUSE THIS ? I HAVE
GOOD COMPRESSION, FUEL PRESSURE, SPARK, AIR -
NO SMOKE FROM TAIL PIPE , NO VALVE TRAIN NOISES
JUST A DEAD SPARK PLUG -

[dnguyen1963]

I assumed that you have put in a new spark plug and the symptom persists. Have you check the spark plug wire? If your wire is okay then I would look at the distributor and cap.

[Mthrizzle]

I assumed that you have put in a new spark plug and the symptom persists. Have you check the spark plug wire? If your wire is okay then I would look at the distributor and cap.

YES I HAVE, WIRES, PLUGS, CAP AND ROTOR BUTTON :up:

[I got it, yes!!]

Have you actually checked to see if the injectors working? I had a bad wire(pulled out)on my injector plug and it wasnt working. Something to check if you havent.

[Mthrizzle]

removed injector rail and powered up rail out of car..all injectors working

[Mthrizzle]

Will be checking valves train tomottow ..will update

[Mthrizzle]

heads got to come off- suspect valves