TBI sensors

[blazerboy_4life]

Does anybody have a list of all the sensors on a 350 TBI and possibly what happens when to the engine when they arent running properly? I just bought a 90' ex cab long box 4x4 and it backfires out the tb and misses at speed. It happens less when i keep it in 3rd but still happens. I have already replaced the fuel filter and TPS and that made a difference in running and idleing but not at speed. I just bought plugs and wires last night and I know I should check the timing too. Should be set at 0 degrees right? This is my first time working on a fuel injected engine so I know I have a lot to learn but I pick it up fast.

Also what are the simplest and cheapest things to do for hp and mpg gain?

Heres what Im working with. 90' 5.7 TBI, 700r4, 265/75/16 tires. Currently has manifolds into single exhaust. Not sure about rear end.

Thanks in advance for all the help everyone.