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That's very bizarre that it wouldn't trip any fault codes at all. Well, it can only be 1 of two things: fuel or spark. I don't have a 1999 Factory Workshop Manual in front of me but I do have a 2001 FWM. It has an entire 150+ page section devoted to engine control system troubleshooting.

Engine runs rough/rolling idle:
Improper engine compression
Improper valve timing
Fuel quality
Engine overheating
Air leakage from intake-air system (Loose tubes, cracks, gasket breakage)
IAC valve improper operation
Variable valve timing system malfunction (again, I'm loooking @ '01 manual so may not apply)
Vacuum leakage (Vacuum hose damage, misrouting)
Initial ignition timing misadjustment (CKP sensor and crankshaft pulley misalignment)
Spark plug malfunction (e.g. open, short, cracks)
High-tension leads malfunction (Cracks, open, low resistance)
CKP sensor is damaged (e.g. open or short circuits)
Crank shaft pulley is damaged
Improper gap between CKP sensor and crankshaft pulley
FP malfunction (mechanical or electrical)
Pressure regulator malfunction
Fuel hoses restriction or clogging
Injectors malfunction (Leakage or clogging, inoperative)
Fuel filters restriction or clogging
CMP sensor is damaged (e.g. open or short circuit)
Crankshaft is damaged
Improper air/fuel mixture ratio control
Exhaust system restriction or clogging
EGR system malfunction
EVAP control system malfunction
PCV valve malfunction
TR switch misadjustment
PSP switch and related malfunction
Improper refrigerant amount malfunction
Condenser fan system malfunction
Improper load signal input

Engine runs rough (acceleration/cruise)
CMP sensor is damaged (e.g. open or short circuit)
Improper air/fuel mixture ratio control

Misses (acceleration/cruise)
Ignition coil malfunction (e.g. open, short, cracks)
Spark plug malfunction (e.g. open, short, cracks)
High-tension leads malfunction (Cracks, open, low resistance)
Crank shaft pulley is damaged
Improper gap between CKP sensor and crankshaft pulley
CMP sensor is damaged (e.g. open or short circuit)

Buck/jerk (acceleration/cruise)
No possible factor provided in symptom quick diagnostic chart

Hesitation/stumble (acceleration/cruise)
Pressure regulator malfunction
Improper air/fuel mixture ratio control
MAF sensor and related circuit malfunction

Surges (acceleration/cruise)
Improper gap between CKP sensor and crankshaft pulley
Pressure regulator malfunction
CMP sensor is damaged (e.g. open or short circuit)
Improper air/fuel mixture ratio control


As you can see there are a lot of things you can check. Time to start hooking up your scan tool to monitor sensor outputs when the event occurs.
 

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Supporting Member
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12,196 Posts
Haha. Yeah, driveability issues are tough especially if you have no fault codes to steer you in the right direction. All that stuff I typed up above was from the easy fix section of the service manual. The other 148 pages deal with the complicated troubleshooting stuff.
 
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