1998 taco bites the dust

i've got a 1998 tacoma reg cab 2.7L 4cyl. 164,000 miles. never did a thing to it as far as maintenance. when i got it at 34000 miles, it had 265 tires on it and they guy before me must have put some kind of lift kit on it because it sits up pretty high. i've been losing power for about the last 10,000 miles. i finally took it in at about 160000 miles and the shop said they were the worst plugs they'd ever seen. the littl metal "L" on top of the plugs were worn down to little nubs. had the fuel injectors cleaned, too. got a little power back after that and now it's starting really rough, idles bad, and sounds like it's going to stall when i come to a stop, although if i keep the RPM's up, i can always keep it goin. runs great once i'm up to speed. had a compression test done and they said one of the cylinders is at 50%. so, i'm trading in the truck- don't want to put more money into it, but for future reference, i'm still curious to know what's going on. any thoughts??? i've got a month to go before my new one arrives- do you think my current truck is gonna make it that long? could it be a result of running it on bad plugs for so long? let's trouble shoot this one guys.

 

oh yeah... i don't know if the previous owner ever regeared it for the 265's. now i've got 31's on it and the spedometer is way off. reads 84 when i'm actually going 75mph. might that have ruined the engine over the lifetime of the truck? or could it be a stuck valve if one of the cylinders wasn't firing due to a bad plug?

 

Try some fuel injection cleaner. I have a 95 tha was running rough with a loss of power and it helped tremendously