Just picked up a high mileage 5.4l 2000 F150 4x4 for $450. Was too cheap to turn down, even if I had to replace motor ...I got several other donor fords in my backyard. It starts rough then settles down and idles good. Driving under acceleration is horrible. If i just let it idle around its ok. If I give it any pedal it shakes and struggles to even move. I drove it home about 4 miles away and was scary lol. Barely even moved. I ended up finding a sweet spot of how much gas to give it and could keep it going about 10-15mph. Anymore and it would bog down. It would shake/shudder a bit when first accelerating from a stop...then it would straighten out. Felt like clogged cats to me but thats the simple solution Im hoping for....But about halfway home It gave a little "poof" sound like a backfire and immediately smelled rotten eggs and then it started driving almost completely normal. It needs a new intake as this one is cracked and leaking coolant. I guess I will start by pulling the cats and gutting them and order a new intake. He said he bought it in this condition which title shows he got it about a year ago, said he didnt have time to mess with it and moving. Said all he has done is put new plugs in it and fuel filter. So.... It was worth the risk to me for the price. Minimal rust and in pretty good shape. Newer tires,new battery, and had a new pioneer deck,mtx amp and subs that are worth the $400 and could sell for what I paid for the truck. Didnt see any major leaks, fluids looked/smelled good. No knocking..... I hope its a relatively easy fix and will last me a few years for winter vehicle while the mustang is put up. So...... Im going to start at the cats. Any other common issues or suggesstions or specific parts I should be looking at as the culprit? I have an e350 that acted similar and ended up having to put in new trigger wheel and replacing timing chain/tensioners while I was in there. Even if I have to do that to this I think it will be worth it if it lasts even just a couple years....but 260k miles so its a gamble. No CEL but will throw scanner on it tomorrow. Any suggesstions or opinions? Thanks!