My Suburban will grow a coral reef on the spark plugs inside a month of daily driving. When the build up gets bad enough it will cause #1 to miss.

This weekend I had problems with it missing and sputtering when under load. It runs fine at low RPMS on flat ground, but trying to climb hills it has issues.

I'm running 5w30 right now because that's what the cap calls for, but I have run heavier oil in the past. Should I go back?

What can I do about the sputtering under load?

This is my daily as well as my race car tow truck and occasional race car sleeping accommodation.

Let's say I had $3000 to spend. Should I swap a motor in this, tune it up/freshen the motor, or just sell it for something else?

Here's the old girl:

 

how many mile on the engine

 

156,000 or so. Compression is in spec but only just

 

95 96 350 had a bad problem with cracked heads.