Hello All, SUMMARY & BACKGROUND Suffering from weaker-than-expected-acceleration and low (rough) idle which is causing a flickering oil light. I recently swapped a ‘98 engine (originally paired to a manual trans) into an ‘01 body (now paired with an auto trans). [This question is not model or engine specific] The ‘98 engine and trans had operated normally with expected power and operation before the swap. After the swap, the engine ran very roughly and died after startup due to 1+ year old fuel which was in the ’01 tank. The fuel was drained and replaced and the engine was able to start and successfully idle without dying. SYMPTOMS The engine now seems to be severely underpowered upon acceleration and a lower than desired idle which makes the oil light flicker (accompanied by what sounds to be a new lifter tick at idle and low RPMs- fades away at higher RPM). When attempting to accelerate to freeway speeds on an incline the trans sometimes drops into the kick-down gear and the engine revs up but does not accelerate as much as you’d expect based on the engine noise being generated and apparent RPMs. In addition- the idle is especially rough when A/C is on, to the point that the car will die in some cases if idling in drive with the A/C running. Regardless of A/C operation, sometimes the car will not slowly pull itself forward while in drive as one would expect. I am unsure if this is an unrelated problem or a symptom of what I'm experiencing. I'd also like to mention that the rough idle, lifter tick, and oil light seem to be less pronounced or nonexistent at startup and while the engine is cold. Perhaps this is because the car is operating in "open loop" fuel maps until it is warmed up. That is just speculation. Hopefully this information is helpful somehow. ATTEMPTED FIXES I’ve attempted the following to remedy the problem. (In this order) 1. Checked engine oil level 2. Checked trans fluid level and color 3. ½ can Seafoam through vacuum hose off intake, ½ can into gas tank 4. Manually increased low idle by adding a small nut shim to the throttle rest bolt 5. Cleaned throttle body 6. The engine had a CEL code for the crank position sensor after the swap. Replaced crankshaft position sensor (CEL light is now off) 7. Replaced spark plugs gapped to .054 PROPOSED FIXES Reading on the forum there have been several suggestions made which could help address the issue. I am hoping to receive help to more precisely isolate the likely cause. 1. Check catalytic converter to see if it is becoming red hot during operation which may indicate it is clogged 2. Replace fuel filter 3. Replace spark wires 4. Clean MAF 5. Check for vacuum leak 6. Replace O2 sensor ACCELERATION VIDEO Below is a link to a video which shows an example of acceleration on a moderate incline. The issue seems to mostly be a lack of power between 20 and 50 MPH. I was applying somewhere around 50% throttle. In this video, the top of the incline is hit at 50 MPH. This was recorded on an off-highway course. I would expect that the car should be able to accelerate up an incline to freeway speeds without so much difficulty and without punching the throttle to 100%. The engine had more pep in it's original chassis/trans. Am I expecting too much? LINK: https://vimeo.com//220673215 SPARK PLUG PHOTO I've also attached a photo of one of the spark plugs I pulled. They all looked very similar to this. From what I can tell, they were simply old and ready to be changed. Attaching the photo in case anyone can derive any more useful information from their condition. QUESTIONS Are there any items I should check or change which would take priority first? Are there other diagnostic checks I can perform for each of the above suggested steps before I invest the money and time to replace/repair each item? What else am I missing? Any advice is greatly appreciated.