2002 Isuzu Rodeo problem..

[s0l0m0nt0mb]

I have a 2002 Isuzu Rodeo that has a new battery..new alternator and a new positive wire cable. What have been happening is I will drive about 10 yards and when I give it gas it just revs. I had my transmission looked at before and the guy said it was fine but you never know like most mechanics will say. I called another mechanic out to my apt and he said its the alarm causing your computer to not relay the information to the transmission to know when to shift. I have a aftermarket Denso alarm and I never heard that a alarm couldve done that. The check engine light is on and I have to replace the egr valve. I also had a whole dianogtisc(sp) done and nothing came up that the transmission needed to be looked at. Any ideas on what I should do next?

[amigo-2k]

does the shift indicator line up correctly on the dash and on the shifter? if not the range selector could be back and could be causing your problem.