I have a 2007 chevy tahoe lt it has the 5.3 vortec and 167000 miles on it bought it used 2 years ago in march thought we were buying a decent vehicle and its letting us down now. Its been using about a quart of oil every few months .i took it for regular oil changes 3 or 4 months ago i had to start changing coil packs and spark plugs and plug wires this past weekend it dropped oil pressure and we had to pull over and shut engine off we got it home and it started missing and was reading randum multiple misfire and a couple of times it read cylinder 7 did the screwdriver injector check and they were all ticking and changed injectors around and no change now its smoking and smells like oil burning is do i have a collapsed lifter or is my motor junk

5300'* aren't known for losing oil pressure randomly. What got it back its oil pressure?

The oil change

You changed the oil and wham, you had oil pressure? Out of curiosity, just how much oil came out when you drained it?

Injectors do not always cause misfires. If you swapped #7 sparkplug with #5, does the misfire follow it? If not, trying doing the same with the sparkplug wire itself. No change? Try swapping the coil pack around.

On another note, what did you use to 'read' these codes? Did you clear them after making repairs(only asking sometimes people see old/past codes and think they are still active)

When i started having problems it was number 2,7 and 1 cylinder i changed out those coil packs and spark plugs that fixed the problem until last week and my low oil pressure pull over and shut off engine came on checked the oil and it was good and i got it home a few days later took the kids to dinner amd it did it again this time it started missing again like it did when i changed out the 1st 3 coil packs and it said cylinder 7 again so i replaced the coil pack again and all the plug wires because the ends were pulling off the wires acts the same way now as having a bad coil pack but it smells like its burning oil now checked it with a actron autoscan plus yes cleared the codes after changing things around bout 4 or 5 quarts came out i was 2,000 miles pass my oil change according to mileage

Is the burning oil smell coming out of the exhaust pipe or more from the engine bay and/or the vents when the blower is on?

What viscosity of oil is in it?

When it tells you the oil pressure is low, does the engine make any knocking/clacking/otherwise unusual and bad sounds?

Has it ever has the oil pressure sending unit replaced that you are aware of?

Is the air filter fairly clean?

Is the mass air flow sensor clean?

What is the fuel pressure with engine off ignition on?

What is the fuel pressure with engine on?

Are the misfires happening during any particular engine activity (cold/hot/idle/slight load/full throttle/etc.) ?

My guess is you have two problems here.

(1) No oil pressure could really be just a bad sending unit. I've seen a lot of bad ones from 2007-2010 in the last year or so. If no bad noises from the engine then this is likely the issue.

(2) Misfire which we are diagnosing, could be a number of things hence the questions above.

my fiancee found my problem #7 cylinder had a collapsed lifter he took the valve cover off and sure enough it wasnt moving like the rest he got it to free up a little and the next day he went to town to get more stuff to try to fix the problem and by the time he got to town it freed itself completely up and it is all better no miss or anything there was buildup and gunk not letting it work properly

Did this fix the oil burning smell as well?

yes it did

Wow. That doesn't make sense to me but I'm not against it. Glad it'* happy again!