Just a quick over view, 89 k5blazer stock 350 tbi. Was and auto trans Swapped in a 465 4 speed. 1ton axles with 4.10 and 37" tires. Have had several irractic issues the last couple of years and have replaced the ecm, distributor and idle air control valve. One of my questions is: Is there a manual transmission prom I should be using? Would it make a difference in performance? This thing is a real dog but have thought it was due to the large heavy tires. Is there any worthwhile mods that don't get into cam swaps ect? The info I have found out there is shady guys on Facebook selling custom chips with either no performance changes or flat out taking your money. And minimal gains that may or mY not be worth the money. Thanks for any info. Currently timing and idle is at factory settings.