I have a 2002 Dakota 4.7 I was at the store and tried starting it and it like almost didn't hold key long enough to start but it caught but was missing and barley running. So I changed both sensors on mass air flow sensor sometimes it starts easily others I hit gas cut still runs bad. So I took covers off and checked timing. Timing is on I had a rocker off so I took valve out and cleaned it was stuck out wouldn't push in at all after cleaned it would pump a bit . Put back together and it started right up but then it misses and smoke from around moter / exhaust flange and tail pipe. It ran perfect and made no noise was good and strong b4 . I'm at my end

 

Getting any codes? Almost sounds like a clogged cat....

Welcome to DF!

 

1495 now but was a couple different ones when it started acting up

 

1495 now but was a couple different ones when it started acting up 351 355 1388

 

P0351 Ignition Coil A Primary/Secondary Circuit Malfunction
P0355 Ignition Coil E Primary/Secondary Circuit Malfunction
P1388 Variable Cam Timing Overretarded (Bank #2)
P1495 TCSPL Solenoid Circuit Malfunction

I am also seeing 1495 is for the leak detection pump...... I have no idea what a TCSPL solenoid is, but, it seems to have to do with carbs..... Which seems a bit odd, I don't know of a single carb application that is OBDII......

 

Yes leak det. It's not throwing the 351 355 I had a rocker arm off of #1 I figured that was it but idk

 

Remove the front O2 sensor from the exhaust. See if it runs any better.

 

Your descriptions are confusing. So you took both valve covers off? Did you find a rocker ejected and lying there or did you pull the rocker off for some reason? Check for damage from the rocker getting into the works!
You couldn't have taken a valve out to clean it without pulling the head, so you must mean the hydraulic lifter. If a lifter is stuck, which it sounds like that's what happened, it's going to keep ejecting the rocker or run like $hit. (You could also have a valve seat issue) . Since you were in there, you should have replaced the entire set of lifters and at this age, the valve stem seals too (cures the smoking). The LDP is underneath the truck. Right under driver's seat if you've got a quad cab.

 

Yes I found it after I took off covers. Yes I took both off and I took off the timing covers to check time. I started it and unplugged the map sensor and it seemed to idle better but now has tick

 

Replace all the lifters.