TBH...I started playing co-op about level 35 and I never played SP after that. I can't imagine playing SP as far as you are. I'd suggest getting a friend to help you. The game says with more people, the more difficult it is. Maybe a little but
I really don't agree with it being THAT much harder.
What part of the road bloack are you on? Because you can use the Monster Vehicle as it target the probes, lancers. etc... try to position yourself back enough that you are out of range of thier weapons but in range with you vehicles weapons and hold down
the trigger and it will keep shooting. You can also target but pressing the a button so the red diamond comes up and locks on. Try also aiming and firing from the gunner seat to get a better angle.
And remember, If you are going up against Shock Troopers, they are pretty much immune to shock weapons, Pyros are immune to fire and Chemical Troopers are immune to Caustic/Acid.
If you have a shock resistant shield, that helps also. My old running crew and I got caught in a never ending loop of dieing, spawning, dieing, spawning, until we figured out that the probes and Lancers were taking down our regular shields in no time.
Those shock troopers are the most annoying ones out of the whole bunch. Like salminio said,try to find a shield thats shock resistant,make sure it has a decent recharge,and capacity. Use weapons like the combustion Hellfire smg to make short work of the
chem and shock troopers,and a pestilent defiler or any weapon with the corrosive element on the pyros.
Well....also...what character are you using.....I know alot of people say it doesn't matter.....but I played single player general knox on playthrough 2 with a siren.....not any other character.....so it might depend on advice people give you depending on
what character you are using in Knox Armory......Since I was a Siren, I used phasewalk alot to go between cover, I forgot the name of it...but make sure to equip the class mod that speeds up the cooldown rate so u can phasewalk fast when needed.....I also
equipped Transfusion grenades to regain health inbetween phasewalk cooldowns and a shield with a quick health regeneration....those four things helped with the staying alive part....now for the killing.....I used a pestilent defiler(corrosive is a must)...but
I used one with a high fire rate and larger clip size rather then a 2 shot high damage pistol. The other weapons were a really good Combustion Hellfire(fire), an Ogre(blast), and my fatal crux shotgun(blast) with very high fire rate and blast damage! Later
on for Crawmerax I used a nice Double *** SMG since it had higher critical hits....anyways....that's a little bit on how I did general knox solo on playthrough 2...but like I said....you need to let us know what character you are using since different characters
play differently and u need different strategies for ech if playing solo.....I tried all four characters but since the siren blasts through quests so fast the other characters just looked to run way too slow.