hey guys looking for some insight on a vortec engine here.

helping a buddy out on his truck as its having some issues

what he has is a 1996 tahoe ls 1500 2wd 5.7l vortec auto a/c 255,000 kms

he recently bought this so ive no idea of the history..

the engine is idling at 2500-3000 rpm and the brake pedal is hard.- obvs vaccum leak assumption, but nothing found that stood out.

i pulled the plugs to see what was happening as he had previously be told there was a burnt valve.

the odd bank was in poor shape 1 was ok, 3 plug was heavly fouled and white,5 plug was heavely fouled and black, 7 was half assed

all the even cyls had decent looking plugs but a bit white for my likes

a comp test revealed #1-180 #3-180 #5-160 #7-80
2,4,6,8 were all 190

ive yet to get a vaccum reading or get the codes pulled as i only had a short time to look at this tonight.

just looking for any info that may help with this or if there is any common issues that may be apart of this, i havent had much experience on the vortec engines.

thanks guys,
chris.